Aspect Ratio Calculator
Find the aspect ratio of any width × height, or scale dimensions while preserving proportions. Great for images, videos, and UI design.
Aspect ratio
Enter original dimensions and the new value for one side. The other side will be calculated automatically.
Original proportion
Scaled dimensions
Original
Scaled
Common aspect ratios
How to use
Find ratio: Enter width and height in pixels — the calculator reduces the dimensions to the simplest W:H ratio using the greatest common divisor.
Scale dimensions: Enter original width and height, then fill in either the new width or the new height. The missing value is calculated automatically so proportions stay exact.
Common ratios: Click any preset to load it into the Find ratio panel instantly.
Use cases
- Resizing images for web without stretching or cropping
- Checking if a video or photo matches a target platform's required ratio (YouTube 16:9, Instagram 4:5)
- Calculating canvas sizes in Figma, Photoshop or CSS
- Verifying responsive breakpoints maintain correct proportions
- Scaling print designs from one page size to another
Limitations
Results are rounded to the nearest whole pixel in Scale mode — sub-pixel values are truncated since screens can't render fractional pixels.
The GCD-based ratio reduction may produce unexpected results for very large prime dimensions (e.g., 1001×1000 won't reduce further).