calculator
Aspect Ratio Calculator
Use the aspect ratio calculator to resize images, thumbnails, social cards, and layouts without stretching.
Find the matching width or height when keeping an image, video, or layout ratio intact for exports, thumbnails, and responsive design checks.
Result
How it works
Enter the original width and height, then fill either target width or target height. The calculator keeps the source ratio fixed and computes the missing dimension by division or multiplication, then shows the reduced aspect ratio label for clarity.
Examples
Widescreen thumbnail
Input: 1920 × 1080, target width 1366
Output: 767.11 height (ratio 16:9)
Widescreen card
Input: 1920 × 1080, target height 1080
Output: 1920 width (ratio 16:9)
Square image
Input: 1080 × 1080, target width 640
Output: 640 height (ratio 1:1)
Print layout
Input: 4 × 3, target width 160
Output: 120 height (ratio 4:3)
Portrait ratio
Input: 1080 × 1920, target width 540
Output: 960 height (ratio 9:16)
Presentation slide
Input: 1366 × 768, target height 432
Output: 768.0 width (ratio 683:384)
Instagram story
Input: 1080 × 1920, target height 500
Output: 281.25 width (ratio 9:16)
FAQ
Do I need to fill both target fields?
No. Fill one target field and leave the other blank.
Why does the output show both width and height?
You can keep both numbers visible, while the copy target is the computed value.
Can I use percentages or decimals?
Yes. Values in decimal form are accepted and calculated consistently.
Does the calculator change the ratio when I input a different target?
No. It preserves the original ratio from width and height.
What if I enter both target width and height?
The calculator returns a validation error because it is not possible to solve both at once.
Why is the ratio label sometimes large numbers?
The label is a simplified integer ratio derived from the source dimensions.
Does this include file metadata or exports?
No. It only computes numeric dimensions in the browser without reading files or metadata.
Can I trust this for production sizing?
Use it for responsive sizing checks. For exact rendering, final checks should still confirm your platform's scaling and unit behavior.