How to calculate a percentile
The nearest-rank method sorts your data from low to high, then finds the rank by multiplying the percentile (as a fraction) by the number of values and rounding up. For 1, 2, 3, 4, 5, 6, 7, 8 at the 50th percentile the rank is ceil(0.50 × 8) = 4, so the value is 4. The 25th, 50th and 75th percentiles have their own names and are handled by the quartile calculator.
How to use this calculator
Enter up to eight numbers, leave unused fields blank, and set the percentile between 0 and 100. The big result is the value at that percentile. For the middle of the high and low, see the midrange calculator.
Order does not matter when typing the values in, since the tool sorts them first. The result is always one of your entries, expressed in the same units as the data.
Percentiles and ranking
A percentile tells you the value below which a given share of the data falls. The 25th, 50th, and 75th percentiles are the quartiles. To gauge how spread the data is relative to its mean, see the coefficient of variation calculator.
Percentiles are most informative with reasonably large data sets. With only eight values each observation covers 12.5% of the distribution, so a small change in the requested percentile can jump straight to the next value.
Frequently asked questions
- How do I calculate a percentile?
- Sort the data, multiply the percentile by the number of values, round up to get the rank, and read off that value. For 1–8 the 50th percentile is 4.
- What is the nearest-rank method?
- It returns an actual data value rather than interpolating between values, by rounding the computed rank up to the next whole position.
- Is the 50th percentile the median?
- With nearest-rank it is very close to the median; for even-sized data sets it may differ slightly from the interpolated median.
- Can I enter any percentile?
- Yes, any value greater than 0 and up to 100. Common choices are 25, 50, 75, and 90.
- Why does my result differ from the one a spreadsheet gives?
- Spreadsheets usually interpolate between neighbouring data points, while this tool uses the nearest-rank method and always returns a value that actually appears in your data. Both are accepted definitions, so quote which one you used.