Image Aspect Ratio Calculator
Find the correct proportions for images with the free Image Aspect Ratio Calculator. Enter the width and height to calculate the aspect ratio and determine matching dimensions without distorting the image. Use it to prepare graphics for responsive websites, video thumbnails, social media posts and design layouts where consistent proportions matter.
What is Image Aspect Ratio Calculator?
Calculate image proportions with this free online Image Aspect Ratio Calculator. Enter an image's width and height to find its aspect ratio and determine matching dimensions without distorting the original proportions. Use it to prepare photos, responsive website graphics, video thumbnails, social media posts, and design layouts. Quickly calculate suitable image dimensions for consistent presentation across different screen sizes.
Why use this tool?
- Enter a width and height to get the simplified ratio, such as 16:9, and its decimal value.
- Enter a new width to get the matching height, or a new height to get the matching width.
- Resize images and video without stretching them.
How to use Image Aspect Ratio Calculator
- Step 1. Enter the original width and height in pixels.
- Step 2. Read the aspect ratio and decimal value.
- Step 3. Enter a new width or height to see the other dimension.
Common use cases
Important notes
- The ratio is simplified by dividing both numbers by their greatest common divisor, after rounding to whole pixels.
- Calculated dimensions are rounded to two decimal places. Round to a whole pixel before using them.
- Common ratios include 16:9, 4:3, 1:1, 3:2 and 9:16. Other sizes may produce a large ratio, which is normal.
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Image Aspect Ratio Calculator FAQ
How do I calculate an aspect ratio?
Divide the width and height by their greatest common divisor. For 1920 × 1080 the divisor is 120, which gives 16:9.
How do I find the height for a new width?
Multiply the new width by the original height and divide by the original width. For a 1920 × 1080 image resized to 1280 wide, the height is 720.
Why does 1366 × 768 give 683:384?
The two numbers share only the divisor 2, so the exact ratio is 683:384. The size is very close to 16:9 but not exactly 16:9.
What aspect ratio is best for social media?
It depends on the platform and the post type. Check each platform's current size guidance, since they change.