Downscaling an image badly is surprisingly easy. The browser’s default drawImage path uses bilinear filtering, which samples too few source pixels when the reduction is large — the result is aliased edges, moiré patterns in fabric and brickwork, and a general mushiness. This tool routes resizing through pica, a Lanczos resampler running at its highest quality setting, and falls back to stepwise halving if pica cannot load.
You can resize by percentage or by exact pixel width. Aspect ratio is always preserved, so an image is never stretched; specifying a width determines the height automatically.
The resampling runs on your own machine. Family photos, ID scans and product shots are never uploaded to a resizing service.
| Use | Typical width | Note |
|---|---|---|
| Website hero image | 1920 px | Covers most desktop displays without waste |
| Blog body image | 1200 px | Sharp on high-density screens at normal column widths |
| Email attachment | 1024 px | Keeps the file small enough to send comfortably |
| Forum or chat | 800 px | Loads instantly, still readable |
| Thumbnail | 300 px | Crop first if the subject is small in frame |
This tool will happily accept a custom width larger than the original, but no resampler can invent detail that was never captured. The result is a smooth, slightly soft enlargement rather than a genuinely sharper picture. For meaningful enlargement use the Upscale Image tool, which applies edge-directed interpolation and sharpening designed specifically for that job.
Not when reducing. Pica’s Lanczos filter samples a wide neighbourhood of source pixels for each output pixel, which keeps edges crisp where the browser’s default scaling would soften them. Enlarging is a different matter — detail that was never recorded cannot be recovered.
You set the width; the height follows from the original aspect ratio. This is deliberate, since forcing both dimensions would distort the picture. Crop the image first if you need a specific shape.
No. A JPG stays a JPG and a PNG stays a PNG. Use one of the conversion tools if you also need a different format.
Roughly with the square of the scale, plus encoding effects. Halving the dimensions removes three quarters of the pixels, which usually cuts the file size by around seventy percent for photographs.
Yes. Add the whole batch, choose Custom, and enter one width — every image is scaled to that width with its own height calculated individually.
No. Pica is loaded once as a JavaScript module and then does all its work in your browser. The images themselves never travel over the network.
