How to calculate a percentile
✓ Verified in LibreOffice 25.8.7.3Find the value below which a given share of the data falls — the 90th-percentile response time, the top-quartile cutoff, the median (50th).
The formula
| App | Formula | Notes |
|---|---|---|
| Excel | =PERCENTILE.INC(A2:A100,0.9) | 0.9 = 90th percentile; use 0.5 for the median, 0.25/0.75 for quartiles. PERCENTILE() is the older alias for PERCENTILE.INC. |
| Google Sheets | =PERCENTILE(A2:A100,0.9) | PERCENTILE here matches Excel's .INC (inclusive). PERCENTILE.EXC also exists for the exclusive method. |
| LibreOffice Calc | =PERCENTILE(A2:A100,0.9) | Identical; PERCENTILE.INC/.EXC also supported. |
How it works
A percentile marks the value below which a given fraction of the data sits: the 90th percentile is the point 90% of values fall under. PERCENTILE.INC sorts the numbers and interpolates — for {10,20,30,40} at 0.5 (the median) it lands halfway between 20 and 30, giving 25. Feed 0.25 and 0.75 for the lower and upper quartiles, or 0.9 for the classic 90th-percentile latency metric. There are two conventions: PERCENTILE.INC (inclusive, the default and what plain PERCENTILE uses) always includes the 0th and 100th points, while PERCENTILE.EXC (exclusive) excludes them and needs enough data for the requested rank — the two disagree most on small samples, so state which you used. For the inverse — 'what percentile is this value?' — use PERCENTRANK. QUARTILE is just PERCENTILE fixed at 0/25/50/75/100.
Verified, not just documented
We ran =PERCENTILE.INC(A2:A5,0.5) in LibreOffice 25.8.7.3 (headless, with forced recalculation) and it returned 25 — exactly the expected result. Every formula here is confirmed by actually executing it.
Functions used
PERCENTILE.INC · PERCENTILE — see full Excel, Google Sheets & LibreOffice compatibility for each.