Image Resize Calculator
Work out new pixel dimensions that keep an image’s proportions — by width, by height, or by percentage.
Keeping proportions when you scale
Almost every resize you make — fitting a photo to a web layout, a social post, or a print box — needs to preserve the original proportions so the image doesn’t look stretched. The rule is simple: scale width and height by the same factor. Fix the side that matters (the width of a column, say) and let the other follow.
To go the other way and read a size back as a clean ratio, use the Aspect Ratio Calculator. If you’re resizing for print, the DPI & Print Size calculator turns pixels into inches and centimetres.
Frequently Asked Questions
How do I resize an image without stretching it?
Change the width and height by the same proportion. If you set a new width, multiply the height by the same factor (new width ÷ original width); if you set a new height, do the reverse. This calculator does that for you: fix one side and it works out the other so the picture keeps its shape and nothing looks squashed.
What is the aspect ratio and why does it matter here?
The aspect ratio is the relationship between width and height — for example 1920×1080 is 16:9. As long as you scale both sides by the same amount, the ratio stays the same and the image looks correct. Changing width and height independently breaks the ratio and distorts the picture.
Why is the new height sometimes a fraction of a pixel off?
Pixels are whole numbers, so a proportional height rarely lands on an exact integer and has to be rounded to the nearest pixel. That rounding can shift the resized ratio by a tiny fraction. For most work it is invisible; if you need an exact ratio, pick target dimensions that divide cleanly.
Does resizing up add detail?
No. Enlarging an image (upscaling) stretches the existing pixels over a larger area; it cannot invent detail that was not captured. Reducing an image (downscaling) discards pixels and is generally safe. For big enlargements, start from the highest-resolution original you have.
Educational estimate only. Results are rounded to whole pixels; a real editor may round or resample differently.