Aspect Ratio Calculator
Compute the aspect ratio of any width × height, and resize to a target width or fit inside a maximum box.
Aspect Ratio Calculator — Aspect ratio describes the proportional relationship between width and height. It is the magic number behind "why does this photo look squished?" and "what resolution do I need for an Instagram Reel?".
All math runs locally. No image is uploaded.
What is aspect ratio calculator?
Aspect ratio describes the proportional relationship between width and height. It is the magic number behind "why does this photo look squished?" and "what resolution do I need for an Instagram Reel?".
Enter any two dimensions and the tool reduces them to their simplest ratio (e.g. 1920×1080 → 16:9). You can then resize to a target width, fit inside a maximum box, or look up common preset ratios for social media, print, and video.
How to use it
-
Enter width and height
In any unit — pixels, mm, inches. The ratio is unitless.
-
Read the reduced ratio
The tool uses the GCD of width and height to show the cleanest form.
-
Resize or fit
Pick a target width or max bounds to see the new dimensions.
Examples
1920×1080 video
Full HD video, reduced.
Result: 16:9
1080×1920 Reel
Vertical video for Instagram Reels / TikTok.
Result: 9:16