Image resizer
Resize by pixels or percentage, in your browser. The file never leaves your device.
How it works
Resizing happens on an HTML canvas in this tab. The file is read with createImageBitmap, drawn at the new dimensions, and re-encoded. It is never sent
anywhere — there is no server to send it to.
Downscaling versus upscaling
Downscaling discards information and generally looks fine. Upscaling has to invent pixels; the browser interpolates between neighbours, which produces a blurry approximation. No amount of resizing recovers detail that was never captured.
Choosing a format
- PNG
- Lossless with transparency. Best for screenshots, logos and line art. Large for photographs.
- JPEG
- Lossy, no transparency, excellent for photographs. Quality 80–90% is usually indistinguishable from the original at a fraction of the size.
- WebP
- Typically 25–35% smaller than JPEG at the same visual quality, with transparency support. Supported by every current browser.
Re-encoding a JPEG loses a little each time
JPEG compression is lossy and generational: opening and re-saving repeatedly accumulates artefacts. Resize from the original wherever possible rather than from a previously exported copy.
Transparency and JPEG
JPEG has no alpha channel, so transparent areas are filled with white before encoding. Choosing JPEG for an image with transparency is a one-way change.