Compress PNG

A PNG stores every pixel without loss, and its own compression only removes repetition. To get a real reduction the compressor first reduces the palette: the quality slider sets how many distinct colours are kept, up to 4,096 at quality 100 and about 3,300 at the default 80. Most screenshots, logos and diagrams use far fewer colours than that, so they barely change visually while the file shrinks. If the file is still above the target size, the compressor repeats with a lower colour count and slightly smaller dimensions.

This makes PNG compression on this page lossy, even though the output is a PNG. On smooth gradients and skies you may see banding at low settings; at the default it is rarely visible.

Our test file was a 1200 × 800 photograph saved as PNG, 1,601,750 bytes. Kept as PNG with the defaults it came to 1,032,234 bytes, 36% smaller. Switching the output to JPG gave 125,186 bytes and to WebP 91,364 bytes, both less than a tenth of the original. A 2400 × 1600 PNG photo of 4,348,538 bytes ended up at 945,151 bytes as PNG, mostly because the long side is capped at 1920 pixels by default.

PNG is the right container for screenshots, interface graphics, logos and anything with sharp text or flat colour. For photographs, PNG is the wrong format, and converting to WebP or JPG saves far more than any PNG setting can.

Transparent areas survive when you stay with PNG and also when you choose WebP, which supports an alpha channel. JPG does not, so transparent parts are filled with white; a logo on a transparent background turns into a logo on a white rectangle. For icons and logos on websites, a WebP with transparency is usually smaller than the PNG, and every current browser displays it.

To keep the full resolution, turn on Force original resolution in the settings; otherwise images larger than 1920 pixels on the long side are scaled down. The compressor also hands back the original if its result would not be smaller.

The PNG is decoded, quantized and re-encoded in your browser tab. Screenshots often contain private messages, account numbers or unreleased designs, and none of that is sent to a server. Up to 10 files fit in one batch, 50 MB each; for larger sets, the bulk compressor takes 50.