Free video aspect ratio calculator

The four ratios that matter for social video

9:16 (1080×1920) is the full-screen vertical format of TikTok, Instagram Reels and YouTube Shorts. 16:9 (1920×1080) is the standard horizontal format for YouTube and most screens. 1:1 (1080×1080) is square, still useful for feeds and carousels. 4:5 (1080×1350) is the tall portrait format used in Instagram and Facebook feeds, which takes more screen space than a square without being full screen.

Ratio and resolution are different things: 720×1280 and 1080×1920 are both 9:16. The ratio is the shape; the resolution is the sharpness.

Crop or pad?

When a video doesn’t match the target ratio you have two choices. Cropping keeps the frame full and cuts the edges: turning 16:9 into 9:16 by cropping keeps only about a third of the original width, so the subject has to be in the center. Padding keeps the whole picture and adds bars (letterbox or pillarbox): nothing is lost, but the video looks small on a phone.

The calculator shows both: the crop size with the percentage of the frame you lose, and the padded canvas size with the bar thickness.

How to use the calculator

Type the width and height of your source (or pick a preset). You get the simplified ratio, the closest standard format, and the decimal value. In the resize section, choose a target ratio and enter one dimension: the other one is calculated and rounded to an even number of pixels, which most video encoders require.

Everything is calculated in your browser, instantly.

Tips

Shoot or design for the tallest format you will publish, then crop down: going from 9:16 to 4:5 or 1:1 loses less than going from 16:9 to 9:16. Keep text away from the edges in case a platform crops the preview. And when you export, use the platform’s native resolution (1080×1920 for vertical) rather than an arbitrary size, so the app doesn’t re-scale your video.