Aspect Ratio Calculator
Find a new image height from its original dimensions and your chosen width while preserving proportions.
Calculated Result
Enter your values and calculate.
Simple to use
Get results in seconds
Clear formulas
Understand your results
Works on any device
Mobile, tablet or desktop
How to Use the Aspect Ratio Calculator
Enter the original width and height in pixels, then the desired new width. Calculate to get a width-and-height pair. Apply those dimensions in your image or video editor; this calculator does not upload or resize a file.
Formula and Explanation
New height = New width × Original height ÷ Original width
The original height-to-width proportion is multiplied by the new width. The resulting height is rounded to the nearest whole pixel. Rounding can introduce a small difference from the exact mathematical ratio, especially for very small images.
Positive dimensions are required, and a height that would round below one pixel is rejected. The calculator does not crop an image or improve its resolution. Upscaling can make an image look soft because it does not add original detail.
Worked Example
For an original image of 4032 × 3024 pixels and a new width of 1000 pixels, the height is 1000 × 3024 ÷ 4032 = 750 pixels. Enter 1000 × 750 in your editor to preserve the original 4:3 proportions.
Frequently Asked Questions
Does this tool resize my image file?
No. It calculates dimensions. Open the file in an image editor and use the returned width and height to carry out the resize.
Why is the new height a whole number?
Raster image dimensions use whole pixels, so the calculated height is rounded to the nearest pixel. The entered new width is retained as supplied. Use a whole-pixel width when preparing a raster image.
Can I use it for a video frame?
Yes, it can calculate proportional frame dimensions. Your video codec or platform may require even dimensions or specific sizes; those restrictions are not checked here.
What happens if the calculated height is below one pixel?
If rounding would produce zero, the calculator rejects the dimensions. Increase the new width to obtain a usable pixel height.