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Aspect Ratio Calculator

Calculate image aspect ratios, find a missing width or height, and check against common preset ratios like 16:9 or 1:1.

Runs entirely in your browser — your files are never uploaded to a server.

Last updated

This tool processes your input entirely in your browser. Nothing is sent to our servers.

How It Works

1. Choose Your File

Drag & drop or select the file you want to work with.

2. Processed in Your Browser

Everything happens locally on your device — your file is never uploaded anywhere.

3. Download Your Result

Get your finished file instantly, ready to save or share.

About Aspect Ratio Calculator

Aspect ratio — the proportional relationship between an image’s width and height — determines whether resizing an image will distort it. Knowing the exact target ratio before resizing avoids the common mistake of stretching an image out of proportion.

This tool calculates the correct matching dimension when you know one side and the target ratio (like 16:9 or 4:3) — enter a width, get the correct height that preserves that ratio, or vice versa.

Useful when preparing images for a specific platform requirement (a video thumbnail, a banner ad) where the exact ratio matters, rather than guessing dimensions and checking whether they happen to work.

Frequently Asked Questions

How do I calculate aspect ratio from width and height?

Divide both numbers by their greatest common divisor. For 1920 by 1080 that is 120, which gives 16:9. Type the width and height into this calculator and it shows the simplified ratio and the decimal value (width divided by height) instantly.

How do I calculate the aspect ratio of an image?

Find the image's pixel width and height, for example in its file properties, and enter them in the calculator. It returns the simplified ratio such as 3:2 or 4:3. The tool takes typed numbers and does not read an uploaded image or resize it.

How do I calculate aspect ratio from resolution?

Enter the resolution as width and height. 1920 by 1080 gives 16:9 and 1080 by 1920 gives 9:16. Some resolutions simplify to odd ratios; 1366 by 768 gives 683:384, so compare the decimal (1.7786) with 16:9 (1.7778) to see it is close.

How do I calculate the aspect ratio of a screen?

Enter the screen's pixel resolution, such as 2560 by 1440, which gives 16:9. Use pixels, not diagonal inches. You can also pick a preset ratio (16:9, 4:3, 21:9 and others), enter one dimension and get the matching other dimension.

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