How to calculate a percentage of a number
✓ Verified in LibreOffice 25.8.7.3 ✓ Verified in Google Sheets (2026-08-30)Find what X% of a number is — like 15% of 80.
The formula
| App | Formula | Notes |
|---|---|---|
| Excel (desktop) | =A2*B2 | A2=number, B2=percentage entered as 15% (a percent-formatted cell stores 0.15). |
| Google Sheets | =A2*B2 | Identical. |
| LibreOffice Calc | =A2*B2 | Identical. |
How it works
"15% of 80" is just multiplication: 80 × 0.15 = 12. Typing 15% into a percent-formatted cell stores 0.15 under the hood, which is why plain multiplication works. If your percentage is stored as the whole number 15 instead, divide by 100: =A2*B2/100. The reverse question — "12 is what % of 80?" — is =12/80 formatted as a percentage.
Verified, not just documented
We ran =A2*B2 in LibreOffice 25.8.7.3 (headless, with forced recalculation) and it returned 12 — exactly the expected result. We then ran the same formulas in Google Sheets, executed 2026-08-30: a formula-only workbook goes into Google Drive, which converts it to a Sheet and recalculates every formula with Google’s own engine, and comes back out as .xlsx carrying the values Google computed. It returned 12 for the worked example, the same value LibreOffice produced. Both engines’ numbers on this page are executed results. The Excel formula follows Microsoft’s official documented syntax — we do not run desktop Excel.