Free Image Resizer — Resize to Exact Pixels in Your Browser

How it works

Three steps, and nothing leaves your device.

1
Drop in the image

The current dimensions are filled in for you, so you can see what you are starting from.
2
Enter a width or a height

With the ratio locked, filling in one side calculates the other. Unlock it to stretch to an exact size.
3
Download the resized image

Resampling is done with high-quality smoothing, so downscaled photographs stay sharp.

Downscaling is safe; upscaling is not. Making an image smaller discards data and looks clean. Making it larger invents pixels that were never captured — the result is soft, and no browser-side resizer can fix that. If you need a bigger image, go back to the original file rather than enlarging a small copy.
Match the size your page actually displays. Serving a 4000px-wide image into a 800px-wide column wastes bandwidth on every visit and slows your page. A good rule is to export at twice the display width to stay sharp on high-DPI screens, so 1600px for that 800px column.
Unlocking the ratio distorts the picture. Setting width and height independently stretches or squashes the content. That is occasionally what you want for a background texture, and almost never what you want for a photograph of a person. Crop first if you need a specific shape.
Resize before compressing, not after. Reducing the dimensions removes most of the data; compressing the smaller image then works on far less material and produces a better result for the same file size.

Will resizing reduce the file size?

Usually a great deal — file size scales roughly with pixel count, so halving both dimensions removes about three quarters of the data.

Can I resize to a size larger than the original?

Yes, but the result will be soft. Enlarging cannot recover detail that was never in the file.

Is the aspect ratio kept?

By default yes — type one side and the other follows. Uncheck the box to set both independently.