Aspect Ratio Calculator
✓ Link copiedA quick aspect-ratio calculator for designers, video editors, and developers. Set a target ratio — type it as width : height or tap a preset like 16:9, 4:3, 21:9, or 1:1 — then enter the side you already know and get the matching dimension instantly. Need to go the other way? Feed it a real width and height (say 1920 by 1080) and it reduces the pair to its simplest form using the greatest common divisor, and also shows the ratio as a decimal. It handles decimal ratios such as 2.39:1 for cinematic crops, portrait ratios like 9:16 for social video, and any custom pairing you type in. Free, private, and runs entirely in your browser — nothing you enter is ever uploaded.
Dimensions
1,920 × 1,080
- Width
- 1,920
- Height
- 1,080
- Simplified ratio
- 16 : 9
- Ratio as decimal
- 1.7778
How to use
Choose an aspect ratio by tapping a preset or typing the width and height parts into the two ratio fields. Pick whether you know the width or the height, then enter that value. The result card shows the resolved width × height, the ratio reduced to its simplest whole-number form, and the ratio as a decimal. Use Copy to grab the dimensions.
Frequently asked questions
- How does it solve for the missing side?
- It keeps the chosen aspect ratio fixed. If you know the width, the height is width × ratioHeight ÷ ratioWidth; if you know the height, the width is height × ratioWidth ÷ ratioHeight. For a 16:9 ratio, a width of 1920 gives a height of 1080, and a height of 1080 gives a width of 1920.
- How is a ratio simplified?
- The width and height are divided by their greatest common divisor (GCD) to reduce them to the smallest whole numbers with the same proportion. For example, 1920:1080 has a GCD of 120, so it simplifies to 16:9. Decimal ratios are scaled up to whole numbers first, so 2.39:1 becomes 239:100.
- Is my data sent anywhere?
- No. All the math runs entirely in your browser on your own device. The ratio and dimensions you type are never uploaded to a server.