Is an IQ of 87 low? What the score actually means

Where 87 falls on the IQ scale

On the standard mean-100, SD-15 scale, 87 is 0.9 standard deviations below the mean, which works out to about the 19th percentile. Around 81% of people score at or above it. The 80–89 band accounts for roughly one person in six — it is one of the most populated stretches of the whole scale, which is worth holding onto if the label "low average" reads as unusual. It isn't. The full IQ score chart shows how the bands are laid out.

A single score is a range: 83 to 91

A test score is an estimate with a known imprecision. The standard error of measurement on a good test runs about 3 to 5 points, so a result of 87 genuinely means "somewhere around 83 to 91".

That window straddles a classification boundary: 83 and 91 do not both sit in the same band, so the same person could plausibly be filed under two different labels on two different days. The label is softer than it looks.

Either way, treating 87 as a precise value, or as meaningfully different from 83 or 91, reads a certainty into the number that the measurement does not have.

What separates 80 from 89 — less than you would expect

Nine points sounds like a lot. Across the band it is worth about 14 percentile places, and it corresponds to no visible boundary in how people learn, work or manage daily life. The band exists because someone drew lines every ten points on a continuous curve, not because 79, 84 and 90 mark real transitions.

The practical reading: 87 tells you roughly where a sample of timed reasoning puzzles placed you, and very little about which courses, jobs or responsibilities are open to you. Familiarity with the puzzle formats, effort on the day, and interest in the material move a single result more than most people assume.

What the number leaves out

IQ measures abstract reasoning under time pressure. It does not measure practical competence, accumulated skill, conscientiousness, social judgement, or how well someone holds up under pressure — and those tend to predict how work and study actually go at least as strongly. A score of this kind is one narrow reading, taken once, on one type of task.

Can a score in this range change?

Measured scores do move. Some of that movement is practice and familiarity rather than underlying ability — the second time you see a matrix-reasoning item you know what it wants. Some is real: schooling, health, sleep and language exposure all affect measured performance, and population-level scores rose for most of the twentieth century, which is the Flynn effect. What does not have good evidence behind it is the idea that puzzle drills or brain-training apps raise general reasoning; whether IQ can be improved reviews what actually holds up.