Image Resize Calculator
Calculate new image dimensions that preserve the original aspect ratio when you change the width or height, avoiding stretched or squashed images.
Last reviewed by the Radiatus Cloud team
Calculate resized dimensions that preserve the original aspect ratio.
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Resize images without distortion
When you change the size of an image, keeping the same proportions is essential to avoid stretching or squashing it. This calculator finds the matching dimension that preserves the aspect ratio: enter the original width and height, then set either a new width or a new height, and it computes the other. Resizing a nineteen-twenty by ten-eighty image to a width of eight hundred gives a height of four hundred and fifty, keeping the sixteen-by-nine shape intact.
It also shows the scale factor as a percentage, so you can see how much the image is being reduced or enlarged.
Why aspect ratio matters
Changing width and height independently distorts an image, making faces and objects look stretched or flattened. By locking the aspect ratio, you ensure the resized image looks natural. This is useful when preparing images for a layout with a fixed width, fitting a thumbnail into a box, or scaling a photo for upload while keeping its proportions.
The result is rounded to whole pixels, since images cannot have fractional dimensions. All calculation happens locally in your browser.
Notes
This Image Resize Calculator tool runs entirely in your browser, so nothing you enter is uploaded or stored on a server. The generated output is plain, standards-compliant code that you can copy, paste, edit and reuse freely in your own projects, documents and designs without any attribution or sign-up.
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Frequently Asked Questions
How do I keep the aspect ratio when resizing?
Set one new dimension and let the other be calculated from the original proportions, which this tool does automatically.
What happens if I change width and height freely?
The image is stretched or squashed. Preserving the aspect ratio keeps it looking natural and undistorted.
What is the scale percentage?
It is how much the image is being reduced or enlarged relative to the original, so fifty percent means half the original size.
Why are the dimensions whole numbers?
Images are made of discrete pixels, so dimensions must be whole numbers, and the tool rounds the calculated value accordingly.
Privacy & Security
Everything runs in your browser; nothing is uploaded.
How to Use
Enter the original size, then a new width or height.
Disclaimer: This tool is provided "as is" without warranty of any kind. Results are for educational and utility purposes.
Related Tools
EXIF Viewer
ImageExtract hidden EXIF data (Camera, GPS, Settings) from images.
Favicon Generator
ImageGenerate favicons and app icons at every required size from one source image, with the exact HTML to reference them.
Placeholder Image Generator
ImageGenerate placeholder images at any size with custom colours and label text. Produced in your browser as downloadable files, no external hotlinking.