Resize Image
Resize an image to exact pixel dimensions, or by percentage, keeping the aspect ratio locked if you want.
Fit an image to the exact size a website, marketplace, or profile asks for. Type a width, a height, or both, use the percentage shortcuts, and keep proportions locked so nothing stretches. Runs entirely in your browser.
Your image never leaves your browser — resizing happens on your device.
How to use this calculator
- Choose the image to resize.
- Type a target width and/or height, or tap a percentage shortcut.
- Leave the aspect-ratio lock on unless you deliberately want an exact stretch.
- Click Resize Image and save the result.
The formula
With one dimension given and the lock on: other dimension = original other × (target ÷ original given). For a 4000 x 3000 image resized to width 800, height = 3000 × 800 ÷ 4000 = 600.
Worked example
Resizing a 4000 x 3000 photo to a width of 800 px with the lock on produces an 800 x 600 image — the same 4:3 proportions, exactly one fifth of the width.
Frequently Asked Questions
What does the aspect-ratio lock do?
With the lock on, entering one dimension calculates the other from the original proportions, so the image can never come out stretched or squashed. With it off, the image is forced to exactly the width and height you typed, even if that distorts it.
What happens if I fill in both width and height with the lock on?
The image is fitted INSIDE that box at the largest size that keeps its proportions. A 4000 x 3000 image into a 1000 x 1000 box comes out 1000 x 750 — it touches the width limit and stays proportional.
Can I make an image bigger?
Yes — enter dimensions larger than the original, or use the 200% shortcut. Understand that enlarging cannot invent detail the original does not have, so big upscales look soft. It is still useful for meeting minimum-size upload requirements.
Which format is the resized image saved as?
PNG inputs save as PNG (keeping transparency); everything else saves as JPG at 92% quality. To choose the format yourself, run the result through the Convert Image Format tool.
What size do common sites want?
It varies: many marketplaces want at least 1000 px on the longest side, profile photos are usually displayed at 400 x 400 or smaller, and HD video thumbnails are 1280 x 720. Check the requirement, then resize precisely to it here.