Stanine Score Calculator

A stanine, short for standard nine, places a score on a 1 to 9 scale with a mean of 5 and a standard deviation of 2. It compresses a full distribution into nine bands, where 1 is the lowest and 9 is the highest. Stanines 1 to 3 are below average, 4 to 6 are average, and 7 to 9 are above average.

Multiply the z-score by 2, add 5, round to the nearest whole number, then clamp the result to the 1 to 9 range. In formula form that is stanine = round(2z + 5), bounded by 1 and 9. For example, a z-score of 1 gives 2(1) + 5 = 7, so it lands in stanine 7.

The standard bands cover fixed percentile ranges: stanine 1 is the bottom 4%, 2 is the 4th to 11th, 3 is the 11th to 23rd, 4 is the 23rd to 40th, 5 is the 40th to 60th, 6 is the 60th to 77th, 7 is the 77th to 89th, 8 is the 89th to 96th, and 9 is the top 4%. This calculator first turns your percentile into a z-score, then applies the stanine formula so both inputs agree.

The scale is deliberately coarse so small, meaningless differences in raw scores do not look significant. Each stanine spans a range of percentiles, which means two test takers a few points apart often share the same stanine. That keeps reporting simple but hides fine detail, so check the percentile or z-score when precision matters.

A percentile rank tells you the percent of the group you scored at or above, on a 1 to 99 scale. A stanine groups those percentiles into nine bands centered on 5. A percentile is more precise, while a stanine is easier to read at a glance and less sensitive to tiny score changes.

A stanine of 5 is exactly average. It sits at the center of the scale and covers the middle 20% of scores, roughly the 40th to 60th percentile. Stanines of 6 and 7 are above average, while 8 and 9 are well above average.