Resize an image to the dimensions you need
What this tool does
Set a width, a height, or both, and the image is rescaled inside your browser tab. Aspect ratio stays locked unless you unlock it, and the file never leaves your device.
This browser cannot resize images locally. It needs Web Workers with OffscreenCanvas support, and we will not fall back to resizing on the main thread because that would freeze the page. Please try a current version of Chrome, Edge, Firefox or Safari.
How this works
The resize happens inside a Web Worker in this browser tab, using a Lanczos-style resampling filter, so edges stay smooth instead of going jaggy the way a cheap nearest-neighbour scale does. The image never reaches a server.
- Preset sizes are real platform values, and each one is documented in the source with where it came from — YouTube asks for 3840×2160 for video thumbnails, for instance, not the 1280×720 people often repeat.
- With the aspect ratio locked, the image scales to fit inside the box you type, so nothing is stretched. Unlock it to set an exact width and height.
- Small images are left alone unless you tick Allow enlarging: interpolation can add pixels but not detail.
- A batch resizes every image to the same box, then comes back as a single ZIP.
- Nothing is stored: reloading the page discards everything.
Frequently asked questions
Will resizing make my image smaller in bytes?
Usually, yes — fewer pixels generally means fewer bytes. Resizing and compressing are separate steps here, so you can do both: shrink to the dimensions you need, then set a target file size.
Does enlarging an image add detail?
No. Upscaling can only invent pixels by interpolation, so a photo enlarged past its original size looks softer. The tool keeps the original dimensions by default to avoid that.
Can I resize a batch of images to the same size?
Yes. Give one set of dimensions and every image in the batch is scaled to fit inside that same box, each keeping its own aspect ratio, and the finished files download together as a single ZIP.
Where do the preset sizes come from?
Each one records its source. YouTube's own help pages ask for 3840 x 2160 for video thumbnails and 2160 x 3840 for Shorts, so those are the numbers used here rather than the 1280 x 720 figure that gets repeated. The Instagram presets are worked out from the aspect ratios Instagram publishes, and say so.