Aspect Ratio Calculator

How to use the Aspect Ratio Calculator

1. Type the width and height in pixels into Width and Height (they start at 1920 and 1080).
2. Read the simplified ratio and the four-decimal "Decimal ratio" that update as you type.
3. To size something to a ratio, enter it under Find a missing dimension, or click one of the Common reference ratios to fill it in.
4. Choose whether you know the width or the height, type that value, and read the missing side.

Example: Checking an ultrawide monitor resolution

Enter 3440 as the width and 1440 as the height. The tool reduces the pair by its greatest common divisor and shows 43:18 with a decimal ratio of 2.3889, so it is close to, but not exactly, the 21:9 ultrawide reference. 2560 × 1080 gives 64:27 (decimal 2.3704).

Questions about the Aspect Ratio Calculator

Why do I get an odd ratio like 683:384 instead of 16:9?

The tool shows the exact reduced ratio of the numbers you enter. 1366 × 768 reduces to 683:384 (decimal 1.7786), which is near 16:9 (1.7778) but not identical; compare the decimal values to see how close two sizes are.

Can I enter decimal dimensions?

Yes. Decimals are scaled to whole numbers before reducing, so 100.5 × 50 shows 201:100 with a decimal ratio of 2.0100.

Why does the result disappear?

Both fields must hold a number greater than zero. If either is empty, zero, or negative, the tool shows "Enter a positive width and height." instead of a ratio.

How do I find the height for a given width?

Use Find a missing dimension: enter the ratio, choose Width and type it. 16:9 at a width of 1280 gives a height of 720. If the result isn't a whole number of pixels, the nearest whole number is shown next to it.