How to calculate the discount percentage from two prices
✓ Verified in LibreOffice 25.8.7.3 ✓ Verified in Google Sheets (2026-08-30)Original price and sale price in hand — what percent off is that?
The formula
| App | Formula | Notes |
|---|---|---|
| Excel (desktop) | =1-B2/A2 | A2=original, B2=sale price. Format as a percentage. |
| Google Sheets | =1-B2/A2 | Identical. |
| LibreOffice Calc | =1-B2/A2 | Identical. |
How it works
The sale price is B2/A2 of the original (60/80 = 75%), so the discount is what's missing from 100%: 25% off. It's algebraically the same as (A2-B2)/A2 — dollars saved over original — use whichever reads better to you. The reverse direction (applying a known discount to get a price) is the calculate-a-discounted-price recipe; and note a 25% discount is NOT undone by a 25% increase — that asymmetry lives in the percentage-change recipe.
Verified, not just documented
We ran =1-B2/A2 in LibreOffice 25.8.7.3 (headless, with forced recalculation) and it returned 0.25 — 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 0.25 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.