Aspect ratio calculator
Find an aspect ratio and calculate dimensions for a proportional resize.
Original size
New size
Results
Width : Height
16 : 9
1280 × 720px
Matches the original aspect ratio exactly.
Calculate width and height ratios without an image file.
How to use Aspect ratio calculator
- 01Enter the original width and height.
- 02Choose whether to set the new width or height.
- 03Enter the target value and copy the calculated dimensions.
About Aspect ratio calculator
Reduce width and height to a ratio such as 16:9 or 4:3, and calculate the other dimension when resizing. No image file is needed.
Resizing a 16:9 image to 1,280 px wide
An original width of 1,920 and height of 1,080 gives 16:9. Set the new width to 1,280 to get a height of 720 px. You can also fix the height and calculate the width.
Fractional results are rounded. At 16:9, a width of 1,000 px gives a rounded height of 563 px. For an exact ratio, use matching multiples of 16 and 9.
Resize an image to your calculated dimensionsFrequently asked questions
How are fractional pixels handled?
Results are rounded to the nearest whole pixel, with a note when rounding occurs.
What dimensions are supported?
Enter whole numbers from 1 to 1,000,000. Calculated dimensions below 1 px are rejected.
Is it free to use?
Yes. All tools are free, with no account required.
