Enter original dimensions and one new side — the other is calculated live. Includes common presets like 16:9 and 4:3.
Original size plus one new side.
Enter the original width and height.
The simplified ratio (like 16:9) appears instantly.
Type a new width or new height — the other side is calculated.
Or click a preset like 16:9 to start from a standard ratio.
Built for speed, privacy and reliability — on any device.
Enter a new width or height — the matching side is calculated live.
1920×1080 instantly shows as the clean 16:9 ratio.
One-click presets for 16:9, 4:3, 1:1, 3:2 and 21:9.
Math runs locally — nothing is sent anywhere.
No account, no limits.
The proportional relationship between width and height — 16:9 means 16 units wide for every 9 units tall, at any size.
Pixel dimensions must be whole numbers, so calculated sides are rounded to the nearest pixel.
16:9 for video and slides, 4:3 for older screens and print, 1:1 for social posts, 21:9 for ultrawide.
No. The calculation runs entirely in your browser.
The tool works in all modern browsers including Google Chrome, Mozilla Firefox, Microsoft Edge, Safari and Opera. We recommend keeping your browser up to date for the best experience.
Step-by-step guide with screenshots and tips.
Read guide →Step-by-step guide with screenshots and tips.
Read guide →Step-by-step guide with screenshots and tips.
Read guide →Step-by-step guide with screenshots and tips.
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