Ratio & aspect ratio calculator
Scale a ratio or find a missing dimension.
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Get it as a ready-made Gravity Forms template. Import it, match your colors, publish.
- Import-ready form file
- Step-by-step build guide
- Works with any theme
How it's calculated
A ratio A:B says the first quantity is A ÷ B times the second. To keep a ratio while changing size, multiply the new known value by the other side of the ratio and divide by its own side: a 16:9 image 1920 wide is 1920 × 9 ÷ 16 = 1080 high, and one 1080 high is 1080 × 16 ÷ 9 = 1920 wide. The scale factor is how many times the ratio’s own numbers were multiplied, 120 in that example. The same arithmetic resizes a recipe, a map or a model.
What are the common aspect ratios?
16:9 for HD and 4K video and most screens (1920×1080, 3840×2160); 4:3 for old TVs and iPads; 3:2 for DSLR photos and 6×4 prints; 1:1 for square social posts; 9:16 for phone video and Stories; 21:9 for ultrawide monitors; 2.39:1 for cinema. Paper sizes in the A series are 1:1.414.
How do I resize an image without stretching it?
Change one dimension and let this tool give you the other at the same ratio. If the target has a different ratio, say a 16:9 photo into a 4:5 Instagram frame, you cannot scale your way there: crop to the new ratio first, then scale.
Can I use this for things that are not images?
Yes. A 3:1 water-to-rice ratio with 2 cups of rice: A = 3, B = 1, you know the second value 2, result 6 cups of water. Map scales, mixing concrete, splitting a bill unevenly: anything that is "this many of one for that many of the other".
Results are estimates for informational purposes only and are not financial, medical or legal advice.