Aspect Ratio Calculator
Resize width or height while keeping the same aspect ratio — essential for images, video and screens.
Result
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Aspect ratio —
Simplified —
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How it works
New height = new width × (original height ÷ original width)Frequently Asked Questions
How do I keep aspect ratio when resizing?
Hold the ratio of the original: for a 1920×1080 image (16:9) resized to 1280 wide, the height is 1280 × (1080/1920) = 720. This calculator does it in either direction.
What is 16:9 in pixels?
Any width and height in that proportion: 1920×1080, 1280×720, and 3840×2160 (4K) are all 16:9. Divide width by height — a ratio of about 1.78 is 16:9.
Why does aspect ratio matter?
Changing it stretches or squashes the content. Keeping it preserves how everything looks, which is why 'lock aspect ratio' exists in every image and video tool.