Stackbench Image Resizer
Choose a size mode, drop in your images, and each one is repainted on a canvas at the size you asked for, showing the before and after dimensions and byte counts without uploading anything.
With the ratio locked, each image keeps its own proportions and is scaled to fit inside the size you enter.
Output format follows the source: PNG stays PNG, JPG and WebP keep their type. GIF, BMP, AVIF and SVG become lossless PNG (first frame only).
Quality applies to lossy output only. PNG is lossless, so it stays out of reach.
No images loaded yet. Add files to see the target size before anything is written.
How to use
- Drop images on the drop zone, or press Choose images to add several files at once.
- Pick By dimensions (px) and type a width — with Lock aspect ratio on, the height follows — or switch to By percentage and drag the Scale slider.
- Press a preset such as 1920 × 1080 for a ready-made size, then press Resize images and read the old → new dimensions and byte change on each row.
- Press Download for one file or Download all for the whole set, using Remove or Clear all to start over.
Frequently asked questions
Do my images get uploaded anywhere?
No. Decoding and encoding happen inside the canvas API already in your browser, so the page never makes an upload request. You can disconnect from the network after the page loads and resizing still works.
Will resizing make my pictures look worse?
Downscaling uses high-quality resampling with stepwise halving, so the loss is usually invisible. Upscaling can never invent detail, which is why a target above 4× the source is refused with a reason in the status line instead of quietly producing a blurry file. PNG output stays lossless; for JPG and WebP you set the quality yourself.
What sizes and formats can I use?
JPG, PNG, WebP, GIF, BMP, AVIF and SVG (first frame) work as far as your browser can decode them. Output follows the source format, anything else becomes lossless PNG, and a target above 16384 px on a side or past the browser’s canvas area limit is rejected with an explanation rather than a blank result.
Guides
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