How IQ Scores Are Calculated
By Cogniusy Team — Psychometric Review
An IQ score is not a raw count of correct answers. It's a standard score: your raw performance converted into a position on a bell curve, relative to a large sample of people your age.
The normal distribution
Most IQ tests are scaled to a mean of 100 and a standard deviation of 15. That means:
- About 68% of people score between 85 and 115
- About 95% of people score between 70 and 130
- Scores above 145 or below 55 are rare — under 1% of the population
Why raw scores don't compare across tests
Two people can answer the same number of questions correctly on different tests and end up with different IQ scores, because each test publisher norms its raw-to-standard conversion against its own reference sample. This is also why practicing with varied question formats — number series, matrices, spatial reasoning — matters more than memorizing one test's exact items.
What the number is actually estimating
IQ scores are a proxy for general cognitive ability (often called g), not a single fixed trait. Performance can shift with practice, sleep, stress, and familiarity with the question formats — which is the entire premise behind targeted practice.
If you're prepping for a specific admission test, see our test guides for format-by-format breakdowns.