Image Resizer
Free image resizer. Change a picture's width and height in your browser — fit inside a box, stretch to exact numbers, or scale by percentage. Nothing is uploaded, so the picture never leaves your device.
What it does
Resizing changes how many pixels a picture is made of. Making it smaller throws information away, which is exactly what you want when a 4000-pixel photo is going into a page that shows it at 800. Making it larger invents nothing: the same detail is simply spread over more pixels, which is why an enlarged photo looks soft. The one thing worth guarding is the proportion — a picture squashed to fit a box looks wrong long before anyone can say why, so fitting inside the box is the default here.
How to use it
- Choose a picture from your device. It is read in the browser and goes no further.
- Type a width or a height, pick a common size, or scale by percentage.
- Compare the two sides and download the result.
Frequently asked questions
Why did the height change when I only typed a width?
Because the proportions are kept by default. A picture that is twice as wide as it is tall stays that way, so it never comes out squashed. If you really need both numbers exactly, switch to exact size — and expect the picture to distort if they do not match the original shape.
Can I make a small picture bigger?
You can, and the page will do it, but it will also tell you what you are getting. Enlarging spreads the existing pixels over a larger area. It cannot recover detail that was never captured, so the result looks softer than the original. Anything that claims otherwise is guessing at the missing pixels.
Is the quality better here than elsewhere?
For big reductions, usually yes, because the shrinking is done in steps rather than in one jump. Going from 4000 px straight to 400 px samples too few of the original pixels and leaves hard, jagged edges; halving repeatedly averages them instead. The difference shows on fine detail like hair or text.
Are my pictures uploaded anywhere?
No. The file is read by your browser, redrawn on a canvas and re-encoded right there. There is no upload and nothing is stored, and once the page has loaded it keeps working with the network switched off.
Which file size should I aim for?
Match the size to where the picture will be shown. A full-width photo on a web page rarely needs more than 1600 pixels across; a thumbnail needs a few hundred. Sending a 4000-pixel photo to a page that displays it at 400 wastes the visitor's data and slows the page down for nothing.
Wikipedia — Image scaling
Wikipedia — Aspect ratio
Wikipedia — Image resolution