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Aspect Ratio Calculator

Find the aspect ratio of any size (1920 × 1080 is 16:9) and resize while keeping it.

Aspect ratio

Ratio

16:9 (HD video)

As a number
1.7778
CSS
aspect-ratio: 16 / 9;

Resize to 16:9

1280 × 720

Runs in your browser — nothing you enter is sent to a server.

How the Aspect Ratio Calculator works

Enter a width and a height to get their aspect ratio in its simplest form, as a number, and as the CSS aspect-ratio property. Well-known ratios are named. Then type a new width or height to get the other side at the same ratio, rounded to whole pixels.

Formulas

Simplest ratio

width ÷ d : height ÷ d, where d = greatest common divisor

Resizing

new height = new width × ratio height ÷ ratio width

Examples

Full HD

1920 × 1080 is 16:9 (HD video). At 16:9, a 1280 px wide image is 720 px high, and a 1000 px high one is 1778 px wide.

Social media

1080 × 1350 is 4:5, the portrait format for social posts. 1366 × 768 simplifies only to 683:384 — close to, but not exactly, 16:9.

Frequently asked questions

Why isn't 1366 × 768 exactly 16:9?

Screen makers rounded to convenient sizes. 1366 ÷ 768 is 1.779; 16 ÷ 9 is 1.778.

How do I stop images stretching?

Give the element aspect-ratio and object-fit: cover, or resize the image to the same ratio before uploading.

Can I enter decimals?

Yes: 1.5 × 1 gives 3:2. Decimals are scaled to whole numbers first.

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