# Image Resizer

> An image resizer changes an image's pixel dimensions, optionally keeping the aspect ratio locked. This one decodes and redraws the file on a canvas in your browser, so the image is never uploaded to a server.

Source: https://rankcert.com/tools/image-resizer
Free, no signup. Updated: 2026-08-29

## How to use it

1. Choose an image or drop it onto the box.
2. Enter a width - height follows automatically while the aspect ratio is locked.
3. Download the result. The file never leaves your device.

## Questions

### Is my image uploaded anywhere?

No. Decoding and resizing happen on a canvas in your browser using createImageBitmap. There is no network request, which is why this works offline once the page has loaded.

### Will resizing lose quality?

Scaling down is close to lossless in perceived quality. Scaling up cannot invent detail - a 200px image enlarged to 800px will look soft no matter which tool you use.

### What size should a hero image be?

Match the largest size it actually renders at, then serve it as WebP. A 4000px image displayed at 1200px wastes roughly 90% of its bytes.

### Does it keep transparency?

Yes. Output is PNG, which preserves the alpha channel. Use the WebP converter if you want transparency at a smaller file size.

### What size should images be for a website?

Match the largest size the image actually renders at, then serve WebP. A full-width hero rarely needs more than 1600px wide; a thumbnail displayed at 300px should not be a 3000px file.

### Does resizing an image reduce its file size?

Substantially. File size scales roughly with pixel count, so halving both dimensions cuts the data by about 75%.

### What is the difference between resizing and cropping?

Resizing scales the whole image and keeps everything. Cropping cuts pixels away and changes the composition. Resize to fit a layout, crop to change the framing.

### Will resizing to a different aspect ratio distort the image?

Yes, if you unlock the ratio. Keep the lock on unless you specifically want the stretch.

## Related tools

- [Image Compressor](https://rankcert.com/tools/image-compressor): Compress JPG and PNG images with a live quality slider and see the exact size saving before you download. Everything runs in your browser.
- [SVG to PNG](https://rankcert.com/tools/svg-to-png): Convert an SVG to a PNG at 1x to 8x scale, so logos and icons export crisp at whatever pixel size you need. Runs in your browser.
- [Favicon Generator](https://rankcert.com/tools/favicon-generator): Turn any image into the five favicon sizes browsers and mobile devices actually request, and get the HTML link tags to paste into your head.
- [PNG to WebP](https://rankcert.com/tools/png-to-webp): Convert PNG and JPG images to WebP with a quality slider, and see exactly how many bytes you saved before downloading.
- [WebP to PNG](https://rankcert.com/tools/webp-to-png): Convert WebP images to PNG for tools and platforms that will not accept WebP. Transparency is preserved and nothing is uploaded.
- [Image Color Picker](https://rankcert.com/tools/image-color-picker): Click anywhere on an image to read the exact colour as HEX, RGB and HSL, and keep a palette of everything you picked. Nothing is uploaded.