The IQ test for young adults: how an 18 to 29 year old is scored against their own age band

0 The short answer

A young adult aged 18 to 29 takes an adult IQ battery, either the Wechsler WAIS-5 given by a psychologist or a normed online test, and the decisive point is that each score is read against adults, not against a fixed standard for every age. Pearson lists the WAIS-5 for ages 16:0 to 90:11, so one instrument spans the whole band, and ACIS is one online option with adult norms from age 16, at 15, 30 or 50 dollars for about 45, 110 or 175 minutes (prices read October 29, 2026). Any online score is unsupervised and not clinical, and it cannot promise a career, an admission or a diagnosis.

1 Which IQ Test Can a Young Adult Take?

No IQ test is made only for ages 18 to 29, so the real choice is among four adult routes: a psychologist with a Wechsler battery, a supervised society exam, a free screener, or a normed online battery. The age floors that matter sit below the band. Pearson lists the WAIS-5 for ages 16:0 to 90:11, which means 16 years 0 months through 90 years 11 months, on the product page we read on October 29, 2026. American Mensa says on its testing page, read the same day, that it does not offer testing to anyone under 14. ACIS norms cover ages 16 to 90. Nothing on those pages treats 18 as a boundary, so an 18 year old, a 23 year old and a 29 year old can sit the same instruments.

What changes at 18 is mostly practical. The page on IQ tests for teenagers explains why we recommend that a parent or guardian be involved for anyone under 18, and that recommendation stops applying. The page on IQ tests for college students takes over for readers whose question is about studies and campus services, and it is organized by what a student is trying to do, not by age. Readers who are simply adults, with no school question, are served by the page on IQ tests for adults. This page keeps to one question those pages leave open: how a score is read inside the 18 to 29 band.

The table compares the routes. The cost column carries only figures we opened on October 29, 2026, and where we found no published price we say so. The sibling pages cover readers a decade or more older, on the page about IQ tests for adults over 40, and readers who want to compare scores with others, on the page about IQ tests for friends.

2 What Does Each Route Cost, and What Do You Receive?

The routes differ more in what they return than in what they cost, because only some of them give an IQ score and only one is documented by a professional. A psychologist evaluation is priced as a service, not as a test. We did not find a published adult fee for a WAIS-5 evaluation in a source we could open and verify, so we state none. A reader should ask for a written quote that says whether it covers the intake interview, the testing, the scoring, the written report and a feedback session, and should ask which battery will be used and why.

Pearson's own listing shows why the instrument price explains little of the bill. The same product page lists the WAIS-5 complete kit in print at 1,784 dollars and the qualification level as C, the label Pearson attaches to the product. A clinician buys that kit once and uses it across many clients, so the fee a client pays is mostly the clinician's time. We state this as an inference from the listing, not as a fact Pearson publishes.

The Mensa route is the cheapest supervised one we could verify. Its page lists regular prices of 60 dollars for a proctored local group session and 99 dollars for private electronic testing, and the page also shows a time limited promotion that we do not quote. It says qualifying means scoring at or above the 98th percentile of the general population, and that the organization cannot provide a detailed report with scores, percentile ranks or an IQ score. On a scale with a mean of 100 and a standard deviation of 15, the 98th percentile falls near 131 in our arithmetic from the normal curve. The result is therefore a yes or a no, which suits a young adult who wants membership and not a profile.

Free screeners are the other end. They cost nothing and some are useful for curiosity, but the useful question is the one in the table: does the page say whom the score is compared with, and does it say anything about age? A free IQ test for a 19 year old that returns one number with no named reference group is a game score, and the page on free IQ tests explains what a free route includes and what it leaves out. The ACIS free trial needs no card and allows one trial per person.

ACIS charges once. Quick is 15 dollars, Optimized is 30 dollars and Full Scale is 50 dollars, with no subscription. A Custom Test costs 5 dollars per subtest, and at 10 subtests the Full Scale form costs the same. The refund policy, quoted literally, is: "Full refund within 5 days if the report does not deliver the features described at checkout or a technical issue prevents you from accessing your results." That is a conditional guarantee and not an unconditional money back one. The page on the best online IQ tests compares ACIS with the alternatives a young adult will meet.

3 When Does a Psychologist Evaluation Make Sense at This Age?

A psychologist evaluation is the right route when the question needs professional judgment and documentation, and an online score is the right route when the question is personal curiosity about where you stand. A WAIS-5 evaluation gives an examiner the chance to observe how a person works, to question unusual results and to write a report that other professionals can use. Pearson says on the product page that the Full Scale IQ rests on 7 subtests and takes 45 minutes, and that the 10 primary index subtests take 60 minutes. In a real evaluation that testing sits inside an intake interview, a report and a feedback conversation, so the whole process takes much longer than the test itself. The page on the adult testing process describes the sequence, the wait and the questions to ask.

Pearson's WAIS-5 "by the numbers" sheet puts the normative sample at 2020 examinees. The product page and that sheet do not list the age bands in the norm tables, so we do not state them. Whatever bands the WAIS-5 uses, they are not stated on those two pages. What can be said from a verified source is how an earlier edition handled the young adult years, which the section on age norms below describes. The page on what the WAIS-5 covers explains the age range and how the batteries relate.

The professional ethics sit on the psychologist's side of the desk. The Ethical Principles of Psychologists and Code of Conduct (APA Ethics Code, effective January 1, 2017) says in Standard 9.02(b) that psychologists use assessment instruments whose validity and reliability have been established for use with members of the population tested. Standard 9.06 asks them to take into account the purpose of the assessment and the characteristics of the person assessed when interpreting results, and to indicate any significant limitations of their interpretations. Standard 9.08(a) says they do not base decisions on test results that are outdated for the current purpose. An online test has no psychologist to apply those rules, so a reader has to apply them, and the last two sections of this page turn them into a short checklist.

A young adult might reasonably choose a psychologist when a school, an employer or a clinic has asked for documentation, or when the reader wants someone qualified to interpret an unusual profile. ACIS is not a clinical or diagnostic instrument and is not for school accommodations or hiring. A reader who wants to confirm whether a high result holds up under supervision, and who is considering adult giftedness as a question, will find that question taken up on the page about gifted tests for adults.

4 How Do Age Norms Work Between 18 and 29?

An age normed IQ score compares a person with people of the same age band, so the same raw performance can earn a different standard score at 19 and at 28, and a score always answers the question of how someone stands among their age peers. A raw score is the count of points a person earned on a task. It means little by itself, because tasks differ in difficulty and people differ in age. A publisher therefore tests a large sample, groups it by age, converts raw scores to scaled scores within each group, and combines scaled scores into indices and a Full Scale IQ on the standard scale, with a mean of 100 and a standard deviation of 15. The page on how IQ scores are normed walks through the process in general terms, and the page on average IQ by age explains why the reference group matters.

The young adult years are not one group in these tables. In their paper on peak performance (Hartshorne and Germine, 2015), the authors analyzed the WAIS-III standardization sample, which they describe as 2,450 healthy, cognitively unimpaired Americans aged 16 to 89, with 200 participants in each of these age bins: 16 to 17, 18 to 19, 20 to 24, 25 to 29, 30 to 34, 35 to 44, 45 to 54, 55 to 64, 65 to 69, 70 to 74 and 75 to 79, plus 150 aged 80 to 84 and 100 aged 85 to 89. That is the third edition, now superseded by the WAIS-5. It shows how one adult battery handled the band: ages 18 to 29 fall into three separate bins, 18 to 19, 20 to 24 and 25 to 29, each with its own norms. The authors also describe their own method as using the age-specific normative data in the manuals to turn scaled scores back into raw scores, which is why their peak ages describe raw performance and not standard scores.

This distinction explains a common confusion. A standard score of 100 means average for the person's own age band, at any age. It does not mean the person performs at the same raw level as an average 19 year old. In principle, a reader whose raw speed on a timed task has fallen slightly since 19 could hold a steady standard score, because the comparison group changes with age. That is an implication of how age norms work, not a finding about any person. At the young end of the band, the research in the next section puts raw speed performance near its highest, so a speed score at 18 is measured against a group at or near its raw peak.

The Standards for Educational and Psychological Testing (AERA, APA and NCME, 2014) address this in Standard 5.8: norms, if used, should refer to clearly described populations that include the individuals or groups with whom test users will ordinarily wish to compare their examinees. Its comment says differentiated norms or summary information about differences between gender, racial and ethnic, language, disability, grade or age groups may be useful in some cases. Standard 5.11 adds that if a publisher provides norms, it is the publisher's responsibility to renorm the test with sufficient frequency to permit continued accurate and appropriate score interpretations. The APA Guidelines for Psychological Assessment and Evaluation (2020), in the application text under Guideline 8, say that psychologists consider age, among other characteristics, when selecting and administering tests so that normative comparisons are valid, and that the age of the norms can be an important consideration in choosing a test.

For ACIS, the page on average IQ by age states that scores are standardized within age groups, so that a score of 100 means average performance for people of the same age. The documentation for the battery, including how its norms are organized, is in the technical manual, and we state nothing about it here beyond that. The page on why the standard deviation is 15 explains the scale all of these scores sit on.

5 Do Cognitive Abilities Peak at Different Ages in Your Twenties?

Different abilities peak at different ages, with processing speed highest in the late teens, working memory near 30 and learned knowledge later, so the 18 to 29 band contains abilities at several different stages. The evidence is a single study that combined two kinds of data. Hartshorne and Germine report in the abstract that they used 48,537 web participants and a comprehensive analysis of normative data from standardized IQ and memory tests, and that the results show considerable heterogeneity in when abilities peak: some abilities peak and begin to decline around high school graduation, some plateau in early adulthood and begin to decline in the 30s, and others do not peak until the 40s or later.

The specific findings matter for a young adult. In the WAIS-III norm data, digit symbol coding, the processing speed task, peaked in the late teens, digit span peaked in the early twenties, and vocabulary peaked around 50. In the web experiment that followed, visual and verbal working memory both peaked at around 30 years, significantly later than processing speed and significantly earlier than vocabulary. The authors also report that the five tasks invoking learned knowledge (vocabulary, information, comprehension, arithmetic and similarities) peaked significantly later than nearly every other task in the norm data. A web sample showed a later vocabulary peak, about 65, which the authors discuss as possibly reflecting confounds or differences between birth cohorts.

Three cautions keep the result in proportion. First, the design is cross-sectional: different people of different ages were compared, not the same people followed over time. The authors write that cross-sectional data may be subject to cohort effects, and they tested the concern by comparing datasets collected two decades apart. Digit span and digit symbol coding showed similar ages of peak performance in all datasets, and vocabulary did not. Second, these are group averages, and a particular person can sit anywhere around them. Third, the numbers describe raw performance on specific tasks, not IQ scores, as the previous section explains.

A second line of evidence points the same way on timing. In a paper titled "When does age-related cognitive decline begin?" (Neurobiology of Aging, 2009), Salthouse examines cross-sectional and longitudinal comparisons. He argues that cross-sectional comparisons show lower performance with older age even between the ages of 18 and 60, and that longitudinal studies can hide early decline because gains from prior test experience offset it. His conclusion is that some aspects of age-related cognitive decline begin in healthy, educated adults in their 20s and 30s. The two papers, read together, say that a young adult is not at a flat plateau: some abilities are still rising, some are at their highest, and some may already be changing slowly.

The practical reading is modest. The processing speed domain is the one most tied to age within this band, and the page on a normed processing speed test shows what a timed ACIS subtest feels like. A gap between a speed index and a reasoning index is not by itself a finding, because the reliability of score differences is a separate question, as the section on reading scores explains. Readers who want the later end of the story will find it on the page about IQ tests for adults over 40, and the page on how IQ changes with age sets out the cross-sectional and longitudinal evidence in full.

6 What Does an IQ Test Measure in a Young Adult?

An IQ battery samples several broad abilities of the Cattell-Horn-Carroll (CHC) model and combines them into a Full Scale IQ, and it does not measure how well someone is doing in life, how hard they work or what they have studied. The page on what IQ measures and the page on the CHC model define the abilities. In short, crystallized ability (Gc) is the breadth and depth of acquired knowledge and verbal reasoning, fluid reasoning (Gf) is solving unfamiliar problems, quantitative knowledge (Gq) is numerical knowledge and reasoning, visual processing (Gv) is working with shapes and space, working memory (Gwm) is holding and manipulating information for a few seconds, and processing speed (Gs) is fast, accurate performance on simple tasks.

ACIS reports these as six indices, and each subtest has its own page that describes the task format and nothing more. The Verbal Comprehension Index (VCI) draws on Antonyms, Vocabulary, Information, Synonyms and Similarities. The Fluid Reasoning Index (FRI) draws on Matrix Reasoning, Figure Weights, Visual Number Series, Logic Grid and Complex Relations. The Quantitative Reasoning Index (QRI) draws on Mathematical Achievement and Arithmetic. The Visual Spatial Index (VSI) draws on Visual Puzzles, Layer Rotation and Spatial Comprehension. The Working Memory Index (WMI) draws on Digit Span, Alphanumeric Sequencing and Visual Sequence. The Processing Speed Index (PSI) draws on Symbol Search and Coding. The page on cognitive domains maps each index to its CHC ability.

Four of those subtests show how the abilities in the previous section turn into tasks. Coding is a timed processing speed task: the person matches symbols to numbers using a key, by clicking on-screen number buttons, and the page gives a time limit of 120 seconds after three unscored practice items. Symbol Search is also a processing speed task: the person looks for a symbol that exactly matches one of two targets, or clicks "NO" if none matches, and the page gives 80 puzzles with a 2 minute limit, with a penalty for wrong answers. Digit Span is a working memory task with three audio sections, forward recall, backward recall and putting digits in ascending order. Matrix Reasoning is a nonverbal fluid reasoning task in which the person picks the option that completes a visual pattern, and its page describes the items as visual. Those are the formats; we reproduce no items from any test.

The ACIS technical manual says that verbal and knowledge tasks are affected by English proficiency and educational exposure. For a young adult that line has two consequences. A 19 year old has typically had fewer years of schooling and reading than a 29 year old, and a score on a knowledge based index partly reflects that exposure. Hartshorne and Germine's finding that learned knowledge tasks peak later than most others is the same point from the research side. A modest verbal index at 19 is therefore weaker evidence about ability than a modest fluid reasoning or working memory index, and the profile of indices says more than the total.

An IQ battery does not measure curiosity, creativity, ambition, taste or character, and it does not predict a single life. The next section looks at how much a score at 18 can be expected to move.

7 How Stable Is a Score From the Late Teens Into the Late Twenties?

Rank order on cognitive tests is highly stable from late adolescence onward, so a score at 18 is a reasonable guide to standing at 28, but stable is not the same as fixed. The strongest evidence is the meta-analysis by Breit, Scherrer, Tucker-Drob and Preckel in Psychological Bulletin (2024). Its abstract says the analysis drew on 205 longitudinal studies with 87,408 participants and 1,288 test-retest correlations. For an age of 20 years and a test-retest interval of 5 years, the authors found a mean rank-order stability of .76, and the abstract describes consistently high stability from late adolescence to late adulthood. The abstract does not give a separate estimate for each year between 18 and 29, so we quote none.

Two limits keep the result in proportion. Rank-order stability is a correlation between two measurements of the same people, and .76 squared is about .58, which is our arithmetic and not a figure the authors report. It means about 58 percent of the variation in later scores lines up with the earlier ones, and a large share does not. That is why one person can move by more than they expect between two sittings, and why the confidence interval on a report matters. The second limit is the difference between rank and level. A person's position among age peers can stay almost the same while their raw performance on a speed task slowly changes, which the peak-age research in the previous section describes. Stability in the meta-analysis is about the ordering of people, not about every person staying where they were.

The meta-analysis describes groups and says nothing about an individual's future. A young adult's result on a given day also depends on sleep, effort, practice with the format and measurement error, which the page on reliability and validity explains in general terms. A reasonable reading is that a score taken at 19 describes where the person stood on that day relative to the reference group, with a margin that the confidence interval makes visible. It is a snapshot with a long shelf life, and it is not a verdict.

The APA Ethics Code Standard 9.08(a), quoted in the section on psychologists, adds the practical rule: results that are outdated for the current purpose should not drive a decision. A score from 18 can be a fair reference at 22, but an important decision at 28 should not hang on it alone.

8 How Should an 18 to 29 Year Old Read the Score?

A normed score places a person within a defined age group, and the useful reading combines the Full Scale IQ, the index profile, the percentile and the confidence interval, because no single number carries the whole result. Scores arrive on three scales. A scaled subtest score runs from 1 to 19, with a mean of 10 and a standard deviation of 3. An index score and the Full Scale IQ sit on the standard scale, with a mean of 100 and a standard deviation of 15. A percentile says what share of the reference group scored at or below the person. The three are not interchangeable, and the page on IQ score versus percentile explains why they cannot be averaged. The table converts common standard scores to percentiles. These percentiles are our arithmetic from the normal curve, rounded, and they are not figures from any test.

Every ACIS form reports a 95 percent confidence interval around the Full Scale IQ. The interval is the honest way to read the number, because it says the score sits inside a range. As an illustration only, and not an ACIS figure, consider a hypothetical interval from 95 to 105. In our arithmetic from the normal curve, 95 sits at about the 37th percentile and 105 at about the 63rd, so the same result could describe someone a little below the middle or a little above it. We state no ACIS reliability figure here, and the documentation is in the technical manual.

Precision also depends on how much was measured. A single subtest score rests on one task and is the least precise piece of a report. An index combines several subtests, and a Full Scale IQ combines the most. The Standards for Educational and Psychological Testing (AERA, APA and NCME, 2014) say in Standard 2.3 that for each total score, subscore or combination of scores that is to be interpreted, estimates of relevant indices of reliability and precision should be reported, and the comment adds that when interpretation centers on the peaks and valleys of a profile, the reliability of score differences is critical. A young adult who reads a profile should therefore treat a gap between two indices with caution. The page on index score differences shows how common gaps are, and the page on the General Ability Index explains how that composite differs from the Full Scale IQ.

The APA Guidelines for Psychological Assessment and Evaluation (2020) say in Guideline 7 that psychologists strive to use multiple sources of relevant and reliable information. For a young adult that means a report is one source. Grades, work samples, the opinion of a mentor and the person's own sense of their strengths belong beside it. The page on the IQ score chart lists score ranges and labels, and the IQ percentile calculator converts a number to a place in the distribution.

9 Does a Second Test Change the Score?

Taking a cognitive test again usually raises the score a little, and the gain comes largely from familiarity with the tasks, so a second sitting within a short time says less about change than the first. The best evidence is the meta-analysis by Scharfen, Peters and Holling in Intelligence in 2018. The abstract reports 174 samples from 122 studies, which resulted in 786 test outcomes and an overall sample size of 153,185, with significant retest effects and no further score gains after the third test administration. In the results, the standardized gain for the first retest is 0.33 standard deviations, rising to 0.50 at the third administration and 0.52 at the fourth. The abstract adds that cognitive ability operation and content, equivalence of test forms, retest interval and participant age have a significant influence on the size of the effect.

On a scale with a standard deviation of 15, a gain of 0.33 standard deviations is about 5 points. That conversion is our arithmetic, and the study reports its effects in standard deviation units. The authors also illustrate the spread in the true effect: with a standard deviation of 0.32 around the first retest gain, the range runs from about minus 0.30 to 0.96. A gain of 5 points is therefore an average, and a particular person can gain more, gain less or lose ground. The page on retaking an IQ test takes this question in full and explains why the second score so often runs higher.

For a young adult this matters in three situations. The first is a person who took a school or clinic battery at 16 or 17 and now wants an online score. The two scores come from different instruments with different tasks and different reference groups, so a difference between them is not a gain or a loss. The second is a person who wants to try again after a disappointing result. An immediate retake mostly measures the practice effect, and this page gives no rule about how long to wait because we found none in the evidence. The third is a person who wants to track change across the twenties. Compare scores from the same kind of test taken under similar conditions, keep the gap long, and expect movement in either direction.

The Standards for Educational and Psychological Testing (AERA, APA and NCME, 2014) say, in the chapter on the rights and responsibilities of test takers, that policies concerning retesting should be communicated. A reader should read the terms shown at purchase before paying, and should not buy a second form hoping to improve the first.

10 What Does an Unsupervised Session Need to Go Well?

An unsupervised session works when the conditions match what the test assumes: a quiet room, a working device with sound, enough time for the form, and a person who is rested and willing. The Standards for Educational and Psychological Testing (AERA, APA and NCME, 2014) are explicit about the risk. A comment to Standard 3.4 says that unproctored test administrations, where standardization cannot be ensured, could provide an advantage to some test takers over others, and that results should be interpreted with caution. A comment in the chapter on psychological testing and assessment says the interpreter of the test results should be informed if the test was unproctored. An online test hands those conditions to the test taker, and this page is one way of passing them on.

Sound is the first requirement. Three ACIS subtests present their items as audio and need working sound: Digit Span, Alphanumeric Sequencing and Arithmetic. The Digit Span page recommends headphones or a quiet room, so a volume check belongs before the first subtest. Layer Rotation, by contrast, carries no words at all according to the manual, which may help a reader whose first language is not English, although the test as a whole is English only. The Coding page says that on a phone the device must be in landscape orientation, and a reader who plans to use a phone should check that before starting.

Time is the second. The three forms take about 45 minutes for Quick, about 110 for Optimized and about 175 for Full Scale, and 175 minutes is long for one sitting. ACIS allows breaks, saves progress between subtests and gives 30 days to complete a form, so a long form can be spread across several days. Sleep is the third condition. The meta-analysis by Lim and Dinges in Psychological Bulletin (2010) examined short-term total sleep deprivation, defined as under 48 hours, across 70 articles and 147 cognitive tests. It found effect sizes that ranged from small and nonsignificant, for reasoning accuracy at g of minus 0.125, to large, for lapses in simple attention at minus 0.776. Those are studies of total sleep deprivation and not of an ordinary short night, so we draw no rule from them, but they support starting a session rested. The page on sleep and IQ covers the wider evidence.

The fourth condition is not getting help. A friend who reads along, a calculator on a quantitative task or a quick search for a word changes what is measured, and the report then describes the helped performance. This is one reason that comparing scores with friends calls for the same form and the same conditions, which the page on IQ tests for friends covers. The free trial opens without a card and shows what the format feels like, and finished trial subtests are kept if the person later unlocks a form that includes them.

11 What Can a Young Adult's Score Not Do?

An IQ score cannot choose a career, secure an admission, document a condition or stand in for a supervised evaluation, and treating it as if it could is a misuse of the number. Each limit has a source or a plain reason. For education, the Standards for Educational and Psychological Testing (AERA, APA and NCME, 2014) say in Standard 12.10 that in educational settings a decision or characterization that will have a major impact on a student should take into consideration not just scores from a single test but other relevant information. A reader who is thinking about a degree, a program or a transfer should read that as a limit on what any one score can decide.

For careers, a score describes abilities as of one day, and it is one input among interests, values, grades, health and opportunity. The page on IQ tests and career guidance takes the question further, and we make no promise here that any score opens or closes a path. The page on IQ tests for college students explains the campus side. ACIS is not for hiring, for school accommodations or for admission to high IQ societies, and it is not a clinical or diagnostic instrument. Group statistics, such as the research on peak ages in this page, describe populations and are never individual diagnoses.

For measurement, the age of the result matters. The APA Ethics Code Standard 9.08(a), already cited, warns against basing decisions on results that are outdated for the current purpose, and the stability evidence above shows why: a score at 18 is a good reference for standing at 22 and a weaker basis for a decision at 29.

Young adults also meet many products that look like IQ tests and are not. Reaction time games, memory games and brain training apps measure something, but a score on one of them is not an IQ unless the product reports a norm referenced score, so check whether it names its reference group. A reader who plays competitive games will find that audience addressed on the page about IQ tests for gamers. For a reader who asks whether the test differs for an 18 year old boy or a 19 year old girl: none of the product pages we read describes a separate version by sex. The things that change the comparison are age, the instrument and the conditions.

Finally, a score says nothing about worth. A young adult with a high number is not more valuable, and one with a low number has not been told something final. The page on the average IQ describes populations, and the research in this page shows that even within the twenties different abilities are on different trajectories.

12 Where ACIS Sits, and What a Buyer Should Do

ACIS is one normed online option for an adult aged 18 to 29, with real strengths and plain limits, and the decision to use it belongs to the reader. The strengths are concrete. It offers a Full Scale IQ and six primary indices with percentiles and a 95 percent confidence interval, and it covers all six CHC domains in its Full Scale form. It is a one time payment with no subscription: Quick is 15 dollars for 6 subtests in 3 domains and about 45 minutes, Optimized is 30 dollars for 13 subtests in 5 domains and about 110 minutes, and Full Scale is 50 dollars for all 20 subtests in six domains and about 175 minutes. These prices were read on October 29, 2026 and can change. Every form reports a Full Scale IQ with its 95 percent confidence interval, and any domain completed through a Custom Test returns its full index score. The refund policy is the conditional one quoted above.

The limits are as concrete. ACIS is online and unsupervised, it is not a clinical or diagnostic instrument, it is not for hiring, school accommodations or admission to high IQ societies, and it is English only. A psychologist's evaluation is the route when a professional needs documentation. The ACIS report compares a person with its adult norms, which cover ages 16 to 90, and its technical manual documents the battery. The Standards for Educational and Psychological Testing (AERA, APA and NCME, 2014) put the user's responsibility plainly. Standard 5.8 asks that norms refer to clearly described populations and that users know when norms are less appropriate for some individuals, a comment to Standard 3.4 asks for caution when administration is unproctored, Standard 2.3 asks for reliability evidence for each score that is interpreted, and Standard 12.10 asks that a major decision about a student rest on more than one test. The APA Guidelines for Psychological Assessment and Evaluation (2020) and the APA Ethics Code (2017, Standards 9.02, 9.06 and 9.08) say the same about norm groups, interpretation and outdated results. We cite them as the yardstick this page tries to meet and not as endorsements of ACIS.

A buyer should do this, in order:

1. Decide the question. If a school, an employer or a clinic needs documentation, start with a licensed psychologist. If the question is personal, continue.
2. Pick the form that fits. Quick for a first look, Optimized for a broader profile, Full Scale for all six indices and the full set of 20 subtests. The page on the best online IQ tests compares alternatives, and the page on IQ tests for adults describes the wider adult category.
3. Start with the free trial. It needs no card and shows the format before anything is spent.
4. Set up the room. Quiet, working sound, a rested start and a plan for breaks.
5. Read the report as one source. Keep the confidence interval in view, compare the index profile and not only the total, and do not use the number for a decision it cannot support.

13 Sources Behind This Page

Every figure above is traceable to one of the following, and each is linked at the point where it is used. Prices and age ranges were read on October 29, 2026 and can change. Any figure we derived ourselves is labeled in the text as our arithmetic.

• Pearson Assessments. Wechsler Adult Intelligence Scale, Fifth Edition (WAIS-5) product page. Age range, completion times, qualification level and kit price, read October 29, 2026.
• Pearson Assessments. WAIS-5 "By the numbers". Normative sample size and administration times, read October 29, 2026.
• American Mensa. Take the Mensa Admission Test. Minimum age, qualifying percentile, regular fees and what is reported, read October 29, 2026.
• Hartshorne J, Germine L. When Does Cognitive Functioning Peak? The Asynchronous Rise and Fall of Different Cognitive Abilities Across the Life Span. Psychological Science, 2015, volume 26, issue 4, pages 433 to 443 (author manuscript open in PubMed Central, PMC4441622).
• Salthouse T. When does age-related cognitive decline begin? Neurobiology of Aging, 2009, volume 30, issue 4, pages 507 to 514.
• Breit M, Scherrer V, Tucker-Drob E, Preckel F. The stability of cognitive abilities: A meta-analytic review of longitudinal studies. Psychological Bulletin, 2024, volume 150, issue 4, pages 399 to 439.
• Scharfen J, Peters J, Holling H. Retest effects in cognitive ability tests: A meta-analysis. Intelligence, 2018, volume 67, pages 44 to 66.
• Lim J, Dinges D. A meta-analysis of the impact of short-term sleep deprivation on cognitive variables. Psychological Bulletin, 2010, volume 136, issue 3, pages 375 to 389.
• American Educational Research Association, American Psychological Association and National Council on Measurement in Education. Standards for Educational and Psychological Testing, 2014. Standards 2.3, 3.4, 5.8, 5.11 and 12.10 and their comments, and the comments on retesting and on unproctored administration, read in the open access edition.
• American Psychological Association. Ethical Principles of Psychologists and Code of Conduct, 2017 amendment, Standards 9.02, 9.06 and 9.08.
• American Psychological Association. Guidelines for Psychological Assessment and Evaluation, 2020, Guidelines 7 and 8.

14 Frequently Asked Questions