Percentile Calculator
Find any percentile, quartiles and the interquartile range (IQR) of a dataset.
Assumptions used in this calculation
- Interpolation method: Percentiles use linear interpolation between adjacent sorted values (the same method as Excel's PERCENTILE.INC / NumPy's default "linear" method), rather than the "nearest rank" method some textbooks use.
About this calculator
Finding a percentile isn't just picking the value at a rounded rank position, most standard methods use linear interpolation between two adjacent sorted values, which is why the 75th percentile of a clean list like 1 through 10 doesn't come out to a round number, and doing that interpolation by hand across a large dataset is fiddly. This calculator sorts the dataset, then finds any requested percentile using linear interpolation (rank = (P ÷ 100) × (n − 1), interpolated between the two closest sorted values), the same method used by Excel's PERCENTILE.INC and NumPy's default "linear" method, rather than the simpler "nearest rank" method some textbooks use. It also reports Q1 (25th percentile), the median (50th percentile), Q3 (75th percentile), and the interquartile range IQR = Q3 − Q1, the spread of the middle 50% of the data, commonly used to flag outliers as values more than 1.5×IQR beyond Q1 or Q3. That produces consistent, interpolated percentile values without manually sorting and interpolating between ranked positions.
Worked example
1-10, 75th percentile
Result: 7.75
How to use this
- 1Paste or type your full dataset, separated by commas or new lines.
- 2Enter the percentile you want to find, for example 90 for the 90th percentile.
- 3Read the interpolated percentile value, calculated using the linear-interpolation method most statistics software uses.
Troubleshooting
My result doesn't match a percentile I calculated by hand or in a spreadsheet.
Different tools use different percentile methods (nearest-rank vs. linear interpolation). This calculator uses linear interpolation, the same method as Excel's PERCENTILE.INC and NumPy's default, check which method your other source uses before comparing.
Can I find what percentile a specific value falls at, instead of the other way around?
This calculator finds the value at a given percentile. To find a value's percentile rank instead, count how many dataset values are below it, divide by the total count, and multiply by 100.
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