Aspect Ratio Calculator

Resize anything proportionally. Lock a ratio (or type your own), enter a width or a height, and get the matching dimension instantly — no stretching, no guesswork. Presets for video, photo and social. Runs in your browser.

Ratio

:
Simplified16 : 9

Dimensions

Type one — the other updates to keep the ratio.

How aspect ratio works

Aspect ratio is the proportion of width to height, written W:H. To resize without distortion you keep that proportion constant: new height = new width × ratio-height ÷ ratio-width. This calculator does it both ways — lock a ratio, type either dimension, and read off the other.

Common resolutions by ratio

RatioUsed forCommon sizes
16:9Video, YouTube, monitors1920×1080, 1280×720, 3840×2160
9:16Reels, Stories, TikTok, Shorts1080×1920
4:3Older displays, some photos1600×1200, 1024×768
3:2DSLR photos, prints3000×2000, 1080×720
1:1Square social posts, avatars1080×1080
21:9Ultrawide monitors, cinema3440×1440, 2560×1080
2.39:1Cinemascope / anamorphic film—
Private by design. The math runs in your browser — nothing is uploaded. This site is static.

Frequently asked questions

How do I calculate aspect ratio?

Divide width by height and simplify: 1920 ÷ 1080 = 1.778 = 16:9. To resize, keep the ratio — width 1280 → height 720.

What is 16:9 in pixels?

It's a ratio, not a size. Common 16:9 resolutions: 1920×1080, 1280×720, 2560×1440, 3840×2160.

How do I resize without stretching?

Keep the same ratio — lock it here, enter the new width, use the height it gives you.

Which ratio for social media?

1:1 square, 4:5 IG portrait, 9:16 Stories/Reels/TikTok/Shorts, 16:9 landscape/YouTube.

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