A free IQ test built on how real cognitive tests are scored
The Lattice Reasoning Test is a free online IQ test with 38 original questions and a 30-minute time limit. It measures fluid reasoning, which is your ability to spot patterns and solve new problems without relying on learned facts. The question formats follow the International Cognitive Ability Resource (ICAR), a public-domain test battery used in psychology research.
What the test covers
- Number and letter series (12 questions). Find the rule behind a sequence such as 2, 3, 5, 9, 17 and give the next term.
- Verbal and logical reasoning (12 questions). Analogies, syllogisms, ordering puzzles and word meaning.
- Matrix reasoning (8 questions). Complete a 3×3 grid of shapes that changes by row and column, similar to Raven's matrices.
- Spatial rotation (6 questions). Tell a rotated shape from its mirror image.
How your IQ score is calculated
Most free IQ tests count your correct answers and look the total up on a fixed chart. This test uses item response theory (IRT), the method behind modern tests such as the GRE.
- Each question has a difficulty rating. A three-parameter logistic model gives the chance that a person of a given ability answers it correctly, and allows for lucky guesses.
- Your ability (θ) is estimated from your full answer pattern using an expected a-posteriori (EAP) estimate. Getting a hard question right counts for more than getting an easy one right.
- θ is converted to the deviation IQ scale used by Wechsler tests: IQ = 100 + 15 × θ. You also get your percentile and a 95% confidence interval.
IQ score ranges
| IQ score | Classification | Share of people |
| 130 and above | Very superior | 2.2% |
| 120–129 | Superior | 6.7% |
| 110–119 | High average | 16.1% |
| 90–109 | Average | 50% |
| 80–89 | Low average | 16.1% |
| 70–79 | Borderline | 6.7% |
| 69 and below | Extremely low | 2.2% |
Frequently asked questions
- How long does the IQ test take?
- There are 38 questions and a 30-minute time limit. Most people finish in 20 to 30 minutes.
- What is an average IQ score?
- IQ scales are set so the average is 100 with a standard deviation of 15. About half of people score between 90 and 109, and about 95% score between 70 and 130.
- Is this online IQ test accurate?
- It gives an informed estimate with a confidence interval, not a clinical result. Question difficulties are expert estimates that have not been calibrated on a norm sample. A formal IQ score requires a professionally normed test such as the WAIS-5, given by a psychologist.
- Is the test really free?
- Yes. The test and the full score report are free. There's no sign-up, email or payment, and your answers stay in your browser.
- Can I retake the test?
- Yes, but the questions are the same each time, so a second score will run higher than your first.