RatioSlateRatio math
Aspect ratio calculator
Enter a width and height. The calculator simplifies the ratio, and lock keeps that proportion while you change either side.
Images are processed locally in your browser.
Direct answer
Calculate the ratio, not the crop
Divide width by height. This page reduces the fraction and, when the result is close to a common shape, names 16:9, 9:16, 4:5, 4:3, or 1:1. It is the math tool. Comparing social crops, focus points, and safe zones belongs on the home workspace or the image tool.
Quick reference
| Formula | width ÷ height |
|---|---|
| Simplify | Greatest common divisor of the two sides |
| Common names | 16:9, 9:16, 4:5, 4:3, and 1:1 when within 1.2% |
| Lock | Changing one side recalculates the other |
| Reverse | Swaps width and height and inverts a lock |
Platform data sources
Working presets and safe-zone guidance are checked against official platform documentation. Safe zones remain conservative guides because app UI varies.
What the result means
1920 × 1080 is 16:9 because 1920 ÷ 120 = 16 and 1080 ÷ 120 = 9. A custom pair such as 3000 × 2000 simplifies to 3:2 and stays labeled custom, because 3:2 is not one of the five named ratios. 1920 × 1200 simplifies to 8:5. That is the same proportion people call 16:10, and the calculator shows the reduced integers 8:5.
Lock is for the other direction. Choose 16:9, keep the lock on, and type a new width. Height becomes the matching 16:9 side. Reverse swaps the two fields, which is the fast path from a landscape ratio to its vertical pair.
What this page does not decide
A ratio is not a resolution. 16:9 describes 1280 × 720, 1920 × 1080, and 3840 × 2160 equally. Pixel count, screen size in inches, and whether a platform will cover the edges are different questions. Use the resolution calculator when you already know the ratio and need pixels. Use the screen calculator for monitor and TV sizes. Use the image tool when the input is a file rather than two numbers.
Examples
1920 × 1080
Simplifies to 16:9. This is the calculator’s starting pair, not a special case.
1080 × 1350
Simplifies to 4:5. Useful when you know the feed pixels and want the name of the shape.
1080 × 1920
Simplifies to 9:16. The vertical ratio page explains the proportion. The 1080 × 1920 page explains that exact pixel grid.
1600 × 1200
Simplifies to 4:3. The 4:3 page starts the tool on this pair so the label and the fields agree.
Frequently asked questions
How is the aspect ratio calculated?
The tool divides width by height, simplifies integer dimensions with their greatest common divisor, and names a common ratio when the value is within 1.2% of 16:9, 9:16, 4:5, 4:3, or 1:1.
Why does 1920 × 1200 not say 16:10?
16:10 and 8:5 are the same proportion. The reduced integer form is 8:5, so that is the label.
Are my images uploaded to a server?
No. Image decoding, reframing, and export happen locally in your browser. The site does not receive your image file.
Which image formats can I use?
You can open JPG, PNG, and WebP images, then export JPG, PNG, or WebP files in supported browsers.