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
Confirm the source dimensions
Enter the original width and height in the same unit. Their relationship defines the source aspect ratio, so swapping width and height also changes the orientation.
Choose one target dimension
Enter either the target width or the target height, not both. The calculator keeps the source ratio and solves the missing dimension from that one constraint.
Review pixel rounding
If the computed result has decimals but your destination accepts only a whole pixel, round once at the end and check that the resulting ratio difference is acceptable.
Choose the next image action
Use proportional resize when the calculated pair is accepted. If the destination requires another shape or byte limit, decide separately whether to crop, pad, resize, or compress instead of forcing both dimensions.
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)
Upload requirement
Input: 1200 × 630 social card, target width 600
Output: 315 height before checking crop, pad, resize, or compress choices
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.
Should I resize or compress after calculating the ratio?
Use the computed dimensions to check the destination requirement first, then decide whether Image Resize, Image Compressor, or a crop/pad workflow is the right next step.