Aspect Ratio Calculator
Work out the aspect ratio of any width and height, such as 1920 × 1080 = 16:9, or calculate the new height for a new width without distorting the image.
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Find the aspect ratio
Resize and keep the ratio
Fill in a common ratio:
How do I calculate an aspect ratio?
To find an aspect ratio, divide the width and height by their greatest common divisor: 1920 × 1080 becomes 16:9. To resize without distortion, multiply the new width by height ÷ width: 1280 × 1080 ÷ 1920 = 720. Enter your numbers and the calculator does both, rounding to whole pixels and showing when it rounds.
- To find a ratio, enter the width and height under “Find the aspect ratio”.
- To resize, enter the original width and height, or tap a common ratio such as 16:9, then choose whether you know the new width or the new height.
- Enter the new size. The calculator fills in the missing side, with a note if it had to be rounded.
Need the right ratio for Stories, video, prints or a website? Read our guide: Image Aspect Ratios: Work Them Out and Choose One
Formulas & Methods
Aspect ratio
Example: 1920 × 1080: d = 120, so 16:9
New height
Example: 1280 × 1080 ÷ 1920 = 720
New width
Example: 480 × 1920 ÷ 1080 = 853.33, rounded to 853
Key features
Exact ratio
Sizes are reduced to their simplest ratio. Awkward sizes such as 1366 × 768 also show the nearest common ratio (about 16:9).
Missing side
Enter a new width or height and get the other one, so an image or video keeps its shape.
Common ratios
Fill in 1:1, 4:3, 3:2, 16:9, 9:16 or 21:9 with one tap.
Rounding shown
Pixels are whole numbers. When the exact result has decimals, it is shown next to the rounded value.
Common aspect ratios
A few ratios cover most screens, photos and videos:
- 1:1: square posts and profile pictures
- 4:3: many phone and compact camera photos, older screens
- 3:2: most DSLR and mirrorless camera photos
- 16:9: HD and 4K video, most monitors and TVs
- 9:16: vertical video for Stories, Reels and Shorts
- 21:9: ultrawide monitors and cinema-style video
Frequently Asked Questions
What aspect ratio is 1920 × 1080?
16:9. Both numbers divide by 120, giving 16 and 9. The same ratio applies to 1280 × 720 and 3840 × 2160.
How do I resize an image without stretching it?
Keep the aspect ratio: work out the new height from the new width with this calculator, then resize to exactly that size. The image resizer can lock the ratio for you.
Why is the result rounded?
Images are made of whole pixels. When the exact size would be, say, 853.33 pixels, the nearest whole number is used and the exact value is shown too.
Is 16:10 the same as 16:9?
No. 16:10 (1.6:1) is slightly taller than 16:9 (1.78:1). Many laptop screens use 16:10.
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Related guides & tutorials
Image Aspect Ratios: Work Them Out and Choose One
Which aspect ratio to use for prints, video, social posts and web pages, how to work one out, and how much of a photo each print size crops off.
How to Resize an Image Without Distorting It
Why images stretch or squash when they are resized, how width, height and aspect ratio fit together, and a workflow that keeps every photo in proportion.