Aspect ratio calculator
Find the ratio of a width and height, or the missing side for 16:9, 4:3 and any other ratio.
Resize, keeping the ratio
Aspect ratio
- As a decimal
- 1.7778:1
- New height
- 720
How it's worked out
Both sides divided by their greatest common divisor: 1,920 × 1,080 → 16:9
New height = 1,280 × 1,080 ÷ 1,920 = 720
- 1Type a width and height, or pick a ratio.
- 2Change one side.
- 3The other side follows.
- Are my numbers private?
- Yes. Every calculation runs in your browser, and what you type stays on your device.
- Does it work offline?
- Yes. Once this page has loaded, it keeps working without an internet connection.
- How exact are the results?
- The maths keeps full precision and only rounds what you see. For loans and taxes, check the final figures with your bank or tax office.
Related tasks
Ready-made settings for common jobs.
Other tools
More calculators for everyday numbers.