Aspect Ratio Finder
Type a width and height, or choose an image, to get its aspect ratio: the simplified ratio, the decimal value and the closest common ratio. Work out a missing width or height, and crop a picture to 1:1, 4:5, 16:9 or another ratio.
- 1Enter a size or an image
- 2Read the ratio
- 3Crop if needed
Find the ratio of a size
- Decimal
- 1.7778 (1.7778:1)
- Closest common
- 16:9, exact
- Shape
- Landscape
Solve for the missing side
At 16:9, a width of 1280 needs a height of 720.
Type a width to get the height, or a height to get the width.
1Choose an image
or drop an image here, or paste one with Ctrl/Cmd+V
Your image never leaves your device. It is measured and cropped in your browser. We count visits and finished downloads (tool name only) with analytics that sets no cookies.
2Pick a ratio
How to find the aspect ratio of an image
- Enter the size, or choose the image. Type the width and height in pixels (or any unit) into Find the ratio of a size. Or choose an image below: its pixel size is filled in for you.
- Read the ratio. The big number is the exact ratio in lowest terms, such as 16:9. The decimal is width ÷ height, and Closest common shows the nearest familiar ratio and how far off it is.
- Crop it if you need another shape. Pick 1:1, 4:5, 3:4, 16:9, 9:16, 3:2 or 21:9, drag the box over the part you want, and download.
How the ratio is worked out
Divide the width and the height by their greatest common divisor. For 1920 × 1080 that is 120, which gives 16:9. For 1366 × 768 it is 2, which gives 683:384: that is not exactly 16:9, but its decimal (1.7786) is within 0.1% of it, so Closest common shows 16:9.
To solve for a missing side, use height = width × ratio height ÷ ratio width, or width = height × ratio width ÷ ratio height. At 16:9, a width of 1280 gives 1280 × 9 ÷ 16 = 720.
Common ratios as pixel sizes
| Ratio | Decimal | Example sizes |
|---|---|---|
| 1:1 | 1 | 1080 × 1080, 512 × 512 |
| 4:5 | 0.8 | 1080 × 1350, 1600 × 2000 |
| 3:4 | 0.75 | 1080 × 1440, 3024 × 4032 |
| 3:2 | 1.5 | 1800 × 1200, 6000 × 4000 |
| 16:9 | 1.7778 | 1280 × 720, 1920 × 1080, 3840 × 2160 |
| 9:16 | 0.5625 | 720 × 1280, 1080 × 1920 |
| 21:9 | 2.3333 | 2520 × 1080, 3360 × 1440 |
About the crop
- Exact ratio: the crop's width and height are whole multiples of the ratio, so a 16:9 crop is exactly 16:9, for example 1920 × 1080 or 992 × 558. Only a very small image can be too small for that; the tool then says the crop is approximate.
- No resizing: the crop keeps the original pixels at their original size. PNG keeps them exactly; JPG is smaller but re-compressed.
FAQ
How do I find the aspect ratio of an image?
Choose the image in the crop box above. The tool reads its width and height in pixels and shows the ratio in lowest terms, such as 4:3, with the decimal value and the closest common ratio. Nothing is uploaded.
Is 1920 × 1080 a 16:9 aspect ratio?
Yes. 1920 ÷ 120 = 16 and 1080 ÷ 120 = 9, so 1920 × 1080 is exactly 16:9. So are 1280 × 720 and 3840 × 2160.
How do I work out the height from the width and a ratio?
Multiply the width by the second number of the ratio and divide by the first. At 4:5, a width of 1080 gives 1080 × 5 ÷ 4 = 1350. Type the ratio and the width into Solve for the missing side to get it straight away.
Why does my image have a strange ratio like 683:384?
The ratio in lowest terms is exact, so sizes that are a few pixels off a common shape give large numbers. 1366 × 768 is 683:384, which is 1.7786 as a decimal, almost the same as 16:9 (1.7778). Closest common tells you which familiar ratio it is near.
How do I crop a photo to 4:5 or 16:9?
Choose the photo, press 4:5 or 16:9, drag the box over the part you want and make it smaller with the Crop size slider if needed. Press Download crop. The file has exactly that ratio.
Does this tool upload my image?
No. Your image is measured and cropped by your browser on your own device and is never sent to a server. You can check: open your browser's developer tools, go to the Network tab, and use the tool. The page counts visits and finished downloads (tool name only) with analytics that sets no cookies, and no image data is ever sent (see privacy).