Are online IQ tests accurate?

Why unsupervised testing loses accuracy

• No one verifies that the conditions were quiet, timed and undistracted.
• Nothing stops a second attempt on questions you have already seen.
• Item difficulty is often calibrated on a self-selected sample rather than a representative one.
• Many sites have a commercial reason to return a flattering number.

Signals that a test is not serious

• Everyone reports a score above 120 — a real distribution centres near 100.
• You have to pay to see the result after finishing the test.
• No time limits anywhere.
• A precise score with no confidence range and no breakdown by ability.
• Wording that guarantees a 'certified' or 'official' IQ.

What a good online test does

• Times each question, so speed is part of the measurement.
• Reports a per-ability breakdown, not a single number.
• States plainly that it is not a clinical instrument.
• Returns results that spread around 100 rather than clustering high.
• Shows you the correct answers afterwards, so the test teaches you something.

So what is it good for?

Three things: getting familiar with question formats before a supervised test, finding out which kinds of reasoning you are relatively weak at, and tracking whether deliberate practice is moving anything. All three are real value. What it cannot do is give you a number to put on an application.

If you need a documented score — for a diagnosis, a school placement, or a high-IQ society — book a supervised assessment with a qualified psychologist. Nothing online substitutes for it, and any site claiming otherwise is telling you something useful about itself.