Aspect Ratio Calculator
Resize while keeping proportions, and find the ratio of any size.
About this aspect ratio calculator
Two related jobs. Given a size and a target width, what height keeps it undistorted? And given a size, what ratio is it actually — is that 1920×1080 really 16:9, or has something been cropped?
There are presets for the ratios that come up constantly: 16:9 for video, 9:16 for vertical, 1:1 for square posts, 4:5 for Instagram portrait, 21:9 for ultrawide and 4:3 for older screens.
How to use it
- Enter your original width and height.
- Type the new width or the new height — the other fills in to match.
- Or pick a preset ratio to lock it to a standard shape.
- The simplified ratio and decimal value are shown underneath.
Aspect Ratio Calculator — FAQ
What aspect ratio is 1920x1080?
16:9. Divide both by their greatest common divisor, 120, and you get 16 by 9.
What ratio should I use for social media?
1:1 or 4:5 for feed posts, 9:16 for stories and short video, 16:9 for YouTube. 4:5 takes up the most feed space of the allowed shapes.
Why does my image look stretched?
Because the new dimensions do not match the original ratio. Use this to find the height that goes with your target width instead of typing both.