IQ Testing for Children: A Parent's Guide

How IQ testing for children differs from adults

The core idea is the same at every age: an IQ score shows how someone's reasoning compares with that of a large group of people. For children, that group is made up of children of exactly the same age, often matched to within a few months. A 7-year-old is compared with other 7-year-olds, and a 12-year-old with other 12-year-olds.

That is why a child's raw performance can grow enormously between 6 and 16 while their IQ score stays roughly the same. The average is fixed at 100 for every age group, as our guide to the average IQ explains. It also means that children's tests have to be built and normed separately for each age band, using thousands of children, which is why they are expensive to make and are given only by trained professionals.

The other big difference is how the test is given. Most adult tests can be taken on paper or a screen, but a young child's attention, reading and confidence vary so much that the most respected children's tests are given one-to-one. The psychologist reads the questions, shows the materials, times the tasks and notes how the child works, not just what they get right.

The main IQ tests for children

The first three are full intelligence tests that produce a Full Scale IQ. The Stanford-Binet 5 measures five factors, fluid reasoning, knowledge, quantitative reasoning, visual-spatial processing and working memory, using a verbal and a non-verbal task for each. The two school tests are group reasoning tests. The CogAT has verbal, quantitative and non-verbal sections, and the CAT4 has four: verbal, non-verbal, quantitative and spatial reasoning. Both are standardised and closely related to IQ, but schools usually report them as their own scores, not as an IQ.

Inside the WISC-V, the most widely used children's test

The Wechsler Intelligence Scale for Children, now in its fifth edition, is the test most parents meet when a child is assessed by a school or clinical psychologist. Its ten primary subtests are grouped into five index scores, each describing a different kind of thinking:

Seven of the subtests feed into the Full Scale IQ. For many children the most useful part of the report is not that single number but the profile across the five indexes, which can show, for example, strong reasoning held back by slow processing speed, a pattern psychologists look at closely when they assess learning difficulties. Our guide to the Wechsler IQ tests explains how index and scaled scores work, using the adult version.

Why children are given IQ tests

Children are rarely tested just to find out their IQ. Testing is usually part of answering a specific question:

• Learning or development concerns. When a child is struggling at school, an assessment can show whether the difficulty is general or specific, for example strong reasoning alongside weak working memory. It is often one part of a wider assessment for special education support, dyslexia or developmental delay, alongside reading, maths and behaviour measures.
• Gifted and advanced programmes. Many school systems use reasoning tests to find children who would benefit from extra challenge. Some children are both gifted and have a learning difficulty, sometimes called "twice exceptional", and a full assessment can reveal both.
• Clinical questions. Psychologists may use an IQ test as part of assessing intellectual disability. Under the DSM-5, that diagnosis depends on both reasoning ability and everyday adaptive functioning, not on an IQ score alone.

If none of these apply and you are simply curious, a professional assessment is rarely worth the cost and the child's time. A fun puzzle activity, like our IQ test for kids, is a better fit for curiosity.

Which test might my child take?

Choose your child's age, the reason you're thinking about testing and where you live to see the tests and next steps that usually apply. It's a general guide, as schools and districts have their own procedures.

How to get a child's IQ tested

Start with the school. Most child IQ assessments begin with a conversation there. Teachers see your child alongside dozens of others of the same age and can tell you whether an assessment is likely to help. They can also explain the school's own tests, which your child may already have taken.

In the United States, if you think your child may need special education, you can ask the school district for an evaluation, verbally or in writing; putting it in writing gives you a record. Under the federal special education law, IDEA, this evaluation is provided at no cost to parents, usually by a school psychologist. If you disagree with the result, you can ask for an independent educational evaluation, which the district may have to pay for. Gifted testing is organised separately by each district, often with a group screening test such as the CogAT for a whole grade, followed by further testing for some children.

In the United Kingdom, talk to your child's teacher or the school's special educational needs coordinator (SENCo). If an assessment is needed, the school can involve an educational psychologist. Many schools also give the CAT4 to whole year groups, and selective schools set their own entrance tests rather than accepting IQ scores.

Private assessments are available from qualified psychologists in most countries. They can be quicker, but prices vary widely. Check that the psychologist is registered, ask which test they will use, and ask for a written report that explains the results and recommendations, not just a number.

Understanding a child's IQ score

Children's IQ scores use the same scale as adults': an average of 100 and a standard deviation of 15. On the WISC-V and WPPSI-IV, the result is described with these labels:

• 130+Extremely highabout 2%
• 120–129Very highabout 7%
• 110–119High averageabout 16%
• 90–109Averageabout 50%
• 80–89Low averageabout 16%
• 70–79Very lowabout 7%
• Below 70Extremely lowabout 2%

Three things help when reading a report. First, every score is an estimate: reports give a range, called a confidence interval, of several points either side, because a child could easily score a little higher or lower on another day. Second, the percentile is often clearer than the IQ itself: a score of 115 is at the 84th percentile, meaning it is higher than about 84% of children of the same age. Third, the index profile often matters more than the Full Scale IQ, especially when the indexes are very uneven.

Giftedness has no single definition. A score of 130, about the top 2%, is the most common benchmark on individual tests, but cut-offs vary between countries, states and districts, and many use a percentile such as the 95th or combine test scores with teacher ratings and schoolwork. At the other end, a score around 70 or below is one part of the picture psychologists consider for intellectual disability, together with how the child copes with everyday tasks. You can explore every level on our IQ scale and score ranges page.

How stable are children's IQ scores?

Children's scores change more than adults', and the younger the child, the more they can move. A 2024 review that combined 205 long-term studies found that the stability of cognitive ability scores was lowest in preschool children and rose through childhood, levelling off from late adolescence. Scores also became less consistent the longer the gap between tests.

By the school years, though, a full IQ test is fairly dependable. In one study of 667 children who were tested twice with the WISC-III for special education, an average of almost three years apart, the Full Scale IQ results correlated at 0.91, and the average scores barely changed. Individual subtests were much less stable than the overall score, which is one reason psychologists warn against reading too much into a single subtest.

For parents, the practical lesson is simple: a preschooler's score is a snapshot of where they are now, not a forecast, and even an older child's score is best treated as a range rather than a fixed label.

Preparing your child for an IQ test

• Make sure they are rested and fed. Tiredness and hunger lower scores, especially in young children.
• Describe it simply. Tell them they will do puzzles and games with someone whose job is to find out how children think, and that nobody gets everything right.
• Don't practise the test itself. Rehearsing the kinds of items used in a specific test can raise a score without changing the child's ability, which makes the result less accurate and less useful for the decisions it is meant to support.
• Mention anything relevant. Let the psychologist know about glasses, hearing difficulties, a second language or recent illness, as these can all affect results.

What online IQ tests for kids can and can't do

No free online test can give a child a genuine IQ score. A real score needs norms from thousands of children of the same age, and a supervised, one-to-one setting that a website can't provide. Many online "IQ tests for kids" give a number anyway, which can mislead parents in either direction.

What a good online activity can do is give children enjoyable practice with patterns, shapes, logic and numbers, and show where their interests and strengths lie. That is why our IQ test for kids gives a puzzle score and a profile, not an IQ, and explains every answer. For teenagers aged 13 and over, our free IQ test uses the adult format, and our article on whether online IQ tests are accurate explains what to look for in any online test.

Frequently asked questions

Sources

• Wechsler Intelligence Scale for Children, Fifth Edition, Pearson: ages, structure and administration time.
• WISC-V UK edition, Education Endowment Foundation measures database: subtests and timing.
• Wechsler Preschool and Primary Scale of Intelligence, Fourth Edition, Pearson: WPPSI-IV age range.
• Stanford-Binet Intelligence Scales, Fifth Edition, PAR: ages and the five factors.
• What is in each battery?, GL Assessment: the four CAT4 batteries.
• Breit, M., Scherrer, V., Tucker-Drob, E. M. and Preckel, F. (2024). The stability of cognitive abilities: a meta-analytic review of longitudinal studies. Psychological Bulletin, 150(4), 399–439.
• Canivez, G. L. and Watkins, M. W. (1998). Long-term stability of the Wechsler Intelligence Scale for Children, Third Edition. Psychological Assessment, 10(3), 285–291.
• Intellectual disability fact sheet, American Psychiatric Association (DSM-5).
• Special education evaluation: an overview, GreatSchools: requesting a free evaluation under IDEA.
• Frequently asked questions, Mensa Canada: the 98th percentile qualifying standard.