About the Image Resize Calculator
New image dimensions that keep the aspect ratio, from a target width, height or percentage.
Also known as: aspect ratio resize, proportional resize calculator, scale image dimensions, resize keeping ratio.
How to use this calculator
- Enter original width, original height, resize by and the other fields.
- The result updates instantly as you type — press Calculate (or Enter) at any time.
- Review the breakdown shown under the main result.
- Use Copy result or Share to save the answer or send a link with your inputs.
Formula
new height = new width ÷ original aspect ratio
Worked example
Using the values pre-filled in the calculator above:
- Original width = 1,920 px
- Original height = 1,080 px
- Resize by: Target width
- Target width = 1,280 px
the calculator returns:
- New dimensions: 1280 × 720 px
- Exact width: 1,280 px
- Exact height: 720 px
- Scale factor: 0.66667 ×