The fastest way
Drop the file into the local image ratio finder. It reads the width and height in your browser, simplifies them, names the nearest common ratio, and shows how well the image fits popular formats. The file is never uploaded.
Finding the pixel dimensions yourself
Windows
- Right-click the image in File Explorer and choose Properties.
- Open the Details tab.
- Look for Dimensions, for example
4032 x 3024.
Mac
- Select the image in Finder and press Command + I (Get Info).
- Expand More Info to see the dimensions.
- Or open it in Preview and choose Tools → Show Inspector.
iPhone and Android
In most gallery apps, open the photo and swipe up or tap the info (ⓘ) button. The details usually show the resolution in pixels. If they don't, the browser tool on this site works on phones too.
From dimensions to ratio
Divide both numbers by their greatest common divisor. For a phone photo of 4032 × 3024, the GCD is 1008, so the ratio is 4:3. For a quick decimal, divide width by height: 4032 ÷ 3024 = 1.333.
| Typical source | Example size | Ratio |
|---|---|---|
| Phone camera (default) | 4032 × 3024 | 4:3 |
| DSLR / mirrorless | 6000 × 4000 | 3:2 |
| Screenshot, 1080p monitor | 1920 × 1080 | 16:9 |
| Vertical video frame | 1080 × 1920 | 9:16 |
| Square social export | 1080 × 1080 | 1:1 |
Why the numbers sometimes look "wrong"
Rotated photos (EXIF orientation)
Phones often save a portrait photo as landscape pixels plus an "orientation" tag that tells viewers to rotate it. Some older tools report the stored size (4032 × 3024) while the photo looks portrait (3024 × 4032). Modern browsers apply the tag, so Ratio Finder Pro reports the size you actually see.
Odd ratios like 1201:799
If an image has been cropped by hand, its dimensions rarely simplify neatly. That's fine. Use the decimal (1.503) to see that it is very close to 3:2.
Does cropping or resizing change the ratio?
- Proportional resizing (both sides scaled equally) keeps the ratio.
- Cropping changes the ratio unless you crop to the same shape.
- Stretching (changing one side alone) changes the ratio and distorts the content.
- Padding (adding borders) changes the canvas ratio without distorting the picture.
The image tool shows roughly how much of an image a crop would remove for each common format. Its formatter lets you pick a destination such as YouTube, Instagram or Reels, choose between keeping the whole image (Fit) and filling the frame (Fill), drag and zoom to position it, then download the exact size.
Frequently asked questions
Does file size tell me the aspect ratio?
No. File size (KB/MB) depends on compression and content. Only the pixel width and height determine the aspect ratio.
Does DPI change the aspect ratio?
No. DPI or PPI only affects how large an image prints. The ratio comes from the pixel dimensions.
Can I find the ratio of an image on a website?
Right-click it and choose Open image in new tab. Many browsers show the dimensions in the tab title. You can also save it and drop it into the image finder.