The short answer
A proper children’s IQ test, such as the WISC-V, is given one to one by a qualified professional and takes over an hour. The score has a mean of 100 and a standard deviation of 15, and it only means something because the test was first given to a large representative sample. A free online test has no such sample and no trained administrator, so any IQ number it shows you is made up. If you want something useful, measure what your child has learned against their school year, and get them familiar with reasoning question formats.
Parents search for a children’s IQ test for sensible reasons. A teacher has said something about potential. A school application mentions cognitive ability. A child seems to find one subject far easier than the rest. This guide explains what an IQ test really is, so you can judge whether you want one, and then covers what else is worth measuring.
What an IQ test actually is
The best known children’s IQ test in the UK is the Wechsler Intelligence Scale for Children, currently in its fifth UK edition and usually called the WISC-V. Pearson publishes it. It is designed for children aged 6 years 0 months to 16 years 11 months, and Pearson describes it as an individually administered clinical instrument. Individually administered means exactly that. One child, one trained examiner, sitting together and working through tasks.
It does not produce a single number and stop. The WISC-V gives a Full Scale IQ, plus five primary index scores that break intelligence into parts, plus three further ancillary index scores. The five primary indexes are verbal comprehension, visual spatial, fluid reasoning, working memory and processing speed. In practice the profile across those five is often more useful to a psychologist than the headline figure.
The scale works the same way as a CAT4 Standard Age Score. The average is set at 100 and the standard deviation is 15. Around two thirds of children score between 85 and 115, and around 19 in 20 score between 70 and 130. If you want that unpacked properly, our guide to CAT4 scores works through the same maths.
Who is allowed to give one
This is the detail that explains everything else. Pearson grades its assessments A, B or C, and will only sell to someone registered as a qualified user. The WISC-V sits at level C, the highest.
| Level | Who can buy and use it |
|---|---|
| A | No special qualification needed. |
| B | A master’s degree in psychology, education, speech and language therapy or a related field with formal assessment training, or an equivalent professional certification. |
| C | A doctorate in psychology, education or a closely related field with formal training in the ethical administration, scoring and interpretation of clinical assessments. Relevant licensure, or membership of bodies such as the BPS, also qualifies. |
On top of that, the British Psychological Society sets the national standards for psychological testing and runs qualifications in test use at three levels: Assistant Test User, Test User and Specialist in Test Use. It keeps a public Register of Qualifications in Test Use, so you can check whether someone offering an assessment actually holds one.
None of that gatekeeping is snobbery. Administering the test is a skill in itself, and so is interpreting it. The same raw performance can mean different things depending on how a child approached the tasks, and only the person in the room sees that.
Why a free online IQ test cannot give a real score
Two reasons, and each one is enough on its own.
The first is the norm group. An IQ score is not a mark. It is a position. Saying a child scored 112 is saying they did better than a particular share of children of the same age, and that share is only known because the test was first given to a large sample chosen to represent the whole population. Test publishers call this standardisation, and the resulting sample is the norm group. A website with no norm group has nothing to place your child against. Any number it displays is a number it invented, however convincing the loading bar was.
The second is the missing examiner. Much of a real assessment depends on watching a child work. A trained examiner notices whether a child gave up early, misread the instruction, or arrived at the right answer by an unusual route. A browser sees a click.
What is worth measuring instead
Most parents searching for a children’s IQ test do not really want an IQ number. They want to know whether their child is doing all right, and what to do about it if not. Those are two different questions, and both have honest answers that do not need a norm group.
What your child has learned
This is the one that changes what you do next week. Our free Skills Check takes about ten minutes and needs no account. Your child answers twenty questions drawn from the UK National Curriculum for their school year, and you get a strand by strand picture of where they are: secure, developing, or needing work, with the actual topic names attached.
It does not give a score out of 100, a percentile, or an IQ figure, and it never will. We have not standardised it on a representative national sample, so any number of that kind would be dishonest. What it gives you instead is more actionable. Knowing that fractions are secure and place value is not tells you what to work on. Knowing that a child is at the 62nd percentile does not.
How your child thinks
This is the part IQ tests and CAT4 both aim at, and you can do something useful here without any score at all. Reasoning questions have a small number of recognisable shapes: sequences, matrices, analogies, odd one out, rotations, reflections and shape codes. A child meeting one of these for the first time in a real test loses time simply working out what is being asked.
Fixing that is cheap. Our guide to non-verbal reasoning question types walks through each format with what the question is really asking. Local authorities that run grammar school tests also publish free familiarisation booklets, and they are the closest thing to the real paper you will find without paying anyone.
What about the CAT4 my school gives?
CAT4 sits between the two. It measures reasoning across four areas, verbal, non-verbal, quantitative and spatial, and UAE school guidance describes it as having similarities to an adult IQ test. It is properly standardised, so its scores are real scores. It is also a group test taken on a computer, not a one to one clinical assessment, and it is not an IQ test. If your child is at a British school in the UAE they will almost certainly sit it. Our CAT4 guide for UAE parents covers when and why.
At what age can a child take an IQ test?
The WISC-V covers ages 6 years 0 months to 16 years 11 months. Other Wechsler tests cover younger and older ages. All of them are given one to one by a qualified professional.
Are free online IQ tests for kids accurate?
No. An IQ score only means something when the test has been standardised on a large representative sample, and free online tests have not been. Without that sample there is nothing to compare a child against, so the number shown is invented.
Who can give my child a real IQ test?
In the UK, tests like the WISC-V are sold only to users at Pearson qualification level C, which means a doctorate in psychology or a closely related field with formal assessment training, or equivalent registration. In practice this usually means an educational or clinical psychologist. The British Psychological Society keeps a public register of qualified test users.
What is a good IQ score for a child?
The scale is built with an average of 100 and a standard deviation of 15, so about two thirds of children score between 85 and 115. A score in that band is ordinary by design. The profile across the different index scores usually tells a psychologist more than the headline number.
Is CAT4 an IQ test?
No. CAT4 measures reasoning and is properly standardised, and UAE school guidance says it has similarities to an adult IQ test. But it is taken in a group on a computer rather than one to one with a psychologist, and it does not report an IQ.
Does Decifer Learning give an IQ score?
No, and we will not. We have not standardised our checks on a representative national sample, so an IQ score, a percentile or any score on a 100 scale would be a made-up number. Our Skills Check reports against the National Curriculum for your child’s school year instead.
Sources
Facts in this guide come from public, verifiable sources. Fees and ratings change: always confirm directly with the school or regulator before making a decision.
- Pearson Clinical Assessment UK: WISC-V UK product information
- Pearson Clinical Assessment UK: qualifications policy (levels A, B and C)
- British Psychological Society: about qualifications in test use
- British Psychological Society: Register of Qualifications in Test Use
- GL Education: standardisation and norms
- WhichSchoolAdvisor UAE: what is the CAT4, and why is my child taking it?