How to find a percentile by hand
- Sort the data from smallest to largest.
- Work out the position: (n − 1) × p ÷ 100, counting from 0.
- If the position is a whole number, that value is the percentile. Otherwise, go the matching fraction of the way between the two neighboring values.
For the sample data (13 values), the 90th percentile position is 12 × 0.9 = 10.8. The values at positions 10 and 11 are 88 and 92, so the answer is 88 + 0.8 × 4 = 91.2.
Percentile rank
Percentile rank = (values below + ½ × values equal) ÷ total × 100
A score of 81 has 8 values below it and 1 equal to it in the sample: (8 + 0.5) ÷ 13 × 100 ≈ 65.4, so it sits at about the 65th percentile.
Where you will see percentiles
- Standardized tests: SAT, ACT and state tests report a percentile next to your score.
- Pay surveys: salary reports often list the 25th, 50th and 75th percentile for a job.
- Website speed: engineers track 95th or 99th percentile load times to catch slow cases.
Want every statistic at once? Use the statistics calculator.
Last reviewed October 2026.
Frequently asked questions
What is a percentile?
A percentile tells you the value below which a given percentage of the data falls. If a score is at the 80th percentile, about 80% of the scores are lower than it.
What is the difference between a percentile and a percentage?
A percentage is a score out of 100, like getting 85% of questions right. A percentile compares you with other people. You could score 85% on a hard test and still be in the 95th percentile if most people scored lower.
Which method does this calculator use?
Finding the value at a percentile uses linear interpolation between data points, the same as the PERCENTILE.INC function in Excel and Google Sheets. Percentile rank counts the values below yours, plus half of any ties, divided by the total.
Is the 50th percentile the median?
Yes. The 50th percentile is the median, the 25th is the first quartile (Q1) and the 75th is the third quartile (Q3), although different quartile methods can give slightly different values.
Can you be in the 100th percentile?
With the rank method used here, the top value in a set approaches but does not reach 100 because ties count as half. Many testing companies cap reports at the 99th percentile for the same reason.