How to calculate a ratio like 16:9
✓ Verified in LibreOffice 25.8.7.3Reduce two numbers to their simplest ratio — aspect ratios, mixes, staffing.
The formula
| App | Formula | Notes |
|---|---|---|
| Excel | =A2/GCD(A2,B2)&":"&B2/GCD(A2,B2) | Whole numbers only (GCD needs integers). |
| Google Sheets | =A2/GCD(A2,B2)&":"&B2/GCD(A2,B2) | Identical. |
| LibreOffice Calc | =A2/GCD(A2,B2)&":"&B2/GCD(A2,B2) | Identical. |
How it works
GCD finds the greatest common divisor (120 for 1920 and 1080); dividing both numbers by it reduces the pair to lowest terms, and & glues them with a colon: "16:9". For a "1 : n" style ratio instead, divide through by the first number: ="1:"&ROUND(B2/A2,2) gives 1:0.56. The result is text — keep the raw numbers in their own cells if you still need to calculate with them.
Verified, not just documented
We ran =A2/GCD(A2,B2)&":"&B2/GCD(A2,B2) in LibreOffice 25.8.7.3 (headless, with forced recalculation) and it returned 16:9 — exactly the expected result. Every formula here is confirmed by actually executing it.