Compress PNG

How to compress PNG files

1. Drop your PNG files onto the page or click Select files.
2. Adjust the compression level if you want to trade a little colour accuracy for smaller files.
3. Click Compress; transparent areas are kept.
4. Compare the result with the original and download the PNGs or a ZIP.

Why PNG files get so big

PNG is lossless and normally stores up to 16 million colours per pixel plus transparency. Screenshots, logos, charts and illustrations rarely need that many distinct colours, yet a full-colour PNG still pays for them in file size.

Colour quantization explained

This tool picks an optimised palette of up to 256 colours that best represents your image and maps every pixel to it, then saves a palette-based PNG. On graphics and screenshots the result usually looks the same and is often 50–80% smaller. It is a lossy step, because colours are approximated. When quantization would not make the file smaller, or would harm an image badly, the tool falls back to saving it losslessly instead.

The approach works best on images with limited colours: interface screenshots, charts, diagrams, icons and flat illustrations. These often contain only a few hundred distinct colours, so a well-chosen palette of 256 is visually indistinguishable from the original.

When PNG isn't the right format

Photographs are a poor fit for PNG. If your image is a photo, convert it with PNG to JPG or PNG to WebP for a far smaller file. Smooth gradients can also show visible banding when reduced to a palette; check them in the before/after comparison.

Frequently asked questions