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Online vs clinical IQ tests
An online IQ test and a clinical IQ assessment both produce a number on the same scale. They are built for different jobs. One gives you a quick, private estimate. The other gives a professional a defensible measurement for decisions that matter. Here is how they differ and how to choose.
Want your own number? The test is 25 visual puzzles, about 12 minutes, no sign-up.
Side by side
| Clinical test | Online test | |
|---|---|---|
| Who gives it | A trained examiner, usually a psychologist | You, on your own device |
| Conditions | Controlled, quiet, supervised | Wherever you are |
| What it samples | A broad battery of verbal and nonverbal tasks | Usually one or a few kinds of reasoning |
| Comparison group | Age-based norms from a large reference sample | Varies by test; often not disclosed |
| Result | Full-scale IQ with a confidence interval and a written report | An estimate, ideally with a range |
| Can be used for | Diagnosis, placement, accommodations, Mensa | Personal interest only |
What a clinical test is
When psychologists talk about an IQ test, they usually mean a full battery such as the Wechsler Adult Intelligence Scale or the Stanford-Binet. The Wechsler scales date to 1939, with WAIS-IV published in 2008 and WAIS-5 in 2024 (Wikipedia: WAIS). The Stanford-Binet traces back to Terman's 1916 revision of Binet's test, and its fifth edition was published in 2003 (Wikipedia: Stanford-Binet).
These tests are given by a trained examiner who follows a standard script, times tasks and records answers. Scores are compared with a large reference sample of people the same age, standardized to a mean of 100 and a standard deviation of 15 (Wikipedia: Intelligence quotient). Even so, the manuals report results with a confidence interval, often around plus or minus 5 points at 95%, because no measurement is exact (Wechsler, 2008).
The point of all that control is defensibility. A clinical score can support a diagnosis, a school decision or an accommodation, because everyone involved knows how it was obtained.
Try one · Quantitative Reasoning
Which number comes next?
10, 17, 26, 37, 50, ?
Tap the option you think is right, or show the answer.
Show the answer
The next number is 65 (option 1).
How to solve it
- The gaps (7, 9, 11, 13) grow by 2 each time, which is the pattern of square numbers.
- Each number is a square number plus 1: 3 × 3 + 1, 4 × 4 + 1, 5 × 5 + 1, 6 × 6 + 1, 7 × 7 + 1.
- So the next number is 8 × 8 + 1 = 65.
That was 1 puzzle. The full test has 25.
What an online test is
An online test runs in your browser, on your schedule, with no examiner. That makes it fast, private and cheap, and it introduces error a clinic removes:
- nobody controls noise, interruptions or how tired you are;
- screen size and touch input change how puzzles look and feel;
- people who have taken many tests are practiced, and retaking cognitive tests raises scores by about a quarter of a standard deviation on average (Hausknecht et al., 2007);
- there is no identity check, so results cannot be used for anything official.
Online tests also vary enormously in quality. Some explain their method and report uncertainty. Many do not. Our guide to how online IQ tests work lists the questions to ask.
When you need a clinical test
- a diagnosis of a learning or intellectual disability, or a related evaluation;
- school placement, gifted programs or testing accommodations;
- legal or medical decisions that ask for a cognitive assessment;
- Mensa admission, which requires a score at or above the 98th percentile on an approved, supervised test (Mensa International).
In each of these cases an online score, however careful, will not be accepted, and it should not be. Start with a licensed psychologist.
When an online test is enough
- you are curious where you sit on the scale;
- you want a private estimate without booking an appointment;
- you want to see how you do on nonverbal reasoning puzzles;
- you want a number to discuss with friends, knowing what it is and is not.
Where IQ Octopus fits
IQ Octopus is an online test, and we say so plainly. It is 25 generated reasoning puzzles, scored with a Rasch model and reported as an estimated IQ with a 95% confidence range. It is not a clinical or diagnostic instrument, is not given by a psychologist, does not apply age norms, and cannot be used for Mensa, school placement, disability assessment or employment screening. We have not run a study comparing it with clinical tests, so we do not quote an accuracy figure.
What it does offer is a careful estimate in about 12 minutes, free to take, with the full result for $4.95 once. Read how it works for the method, or compare the major clinical tests in more detail.
Sources
- Wechsler Adult Intelligence Scale. Wikipedia. en.wikipedia.org/wiki/Wechsler_Adult_Intelligence_Scale
- Stanford-Binet Intelligence Scales. Wikipedia. en.wikipedia.org/wiki/Stanford%E2%80%93Binet_Intelligence_Scales
- Intelligence quotient. Wikipedia. en.wikipedia.org/wiki/Intelligence_quotient
- Wechsler, D. (2008). WAIS-IV Technical and Interpretive Manual. Pearson.
- About us. Mensa International. www.mensa.org/mensa/about-us
- Hausknecht, J. P., Halpert, J. A., Di Paolo, N. T., & Moriarty Gerrard, M. O. (2007). Journal of Applied Psychology, 92(2), 373-385. doi.org/10.1037/0021-9010.92.2.373