Aspect Ratio Calculator

Resize without distortion. Enter your original dimensions and a new width, and this gives the height that keeps the exact same proportions — plus the simplified ratio (like 16:9).

Need more than the free basics? Right dimensions are a detail; great-looking video is the goal. A studio like Riverside records and edits high-quality video and podcasts, sized for every platform.

Try Riverside →

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Common aspect ratios

16:9 is standard for YouTube and most video; 9:16 for Reels, TikTok and Shorts; 1:1 for square feed posts; 4:5 for portrait Instagram. Keeping the ratio when you resize stops images and video from stretching or squashing. Enter your source size and the target width, and this gives the matching height so everything stays in proportion.

Frequently asked questions

How do I keep an image's aspect ratio?

Scale width and height by the same factor. Enter your original dimensions and the new width here, and it calculates the height that preserves the ratio.

What aspect ratio should I use for video?

16:9 for YouTube and landscape video, 9:16 for vertical (Reels, TikTok, Shorts), 1:1 for square posts. Match the platform you're publishing to.

What does a ratio like 16:9 mean?

For every 16 units of width there are 9 of height. It's the simplified form of your dimensions — this tool calculates it for you.

This tool is free and runs entirely in your browser. The link above is an affiliate link: we may earn a commission if you sign up, at no extra cost to you, and it never changes our honest take.