Aspect Ratio Calculator
Working out dimensions for a 16:9 thumbnail or a 4:3 print? Enter any width or height and get the matching dimension instantly — with simplified ratio and common presets.
Ratio Finder
Enter any width and height to get the simplified aspect ratio.
Enter a width and height above to see the ratio.
Simplified ratio
Decimal (W ÷ H)
Scale Calculator
Set the original size (or pick a preset), then enter a new width or height — the other dimension scales automatically.
Presets
Original size
Fill in the original size and one new dimension to see the scaled result.
Exact value
Rounded pixels
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How to use
- Enter the original width and height (or pick a preset ratio).
- Type a new width OR height.
- Get the proportional dimension instantly.
Frequently asked questions
How do I simplify an aspect ratio?
Divide both numbers by their greatest common divisor: 1920×1080 ÷ 120 = 16:9. The tool does this automatically for any input.
What are common aspect ratios?
16:9 (video/YouTube), 4:3 (classic photo), 1:1 (Instagram post), 9:16 (Shorts/Reels/TikTok), 21:9 (ultrawide), 3:2 (DSLR photos). All are one-click presets.
Does it round the results?
Results show exact decimals and a rounded whole-pixel value, so you can choose precision for CSS or whole pixels for exports.