PNG Compressor

What this compressor does, and what it does not

Your PNG is decoded and saved again as a PNG at a standard compression level, not the maximum. Width and height are unchanged. In our tests every visible pixel kept its exact colour and its exact alpha value, so a logo with a soft shadow came back with the same edges. The hidden colour values stored under fully transparent pixels are not guaranteed to survive, but nothing visible depends on them.

It does not reduce the number of colours. That matters because the large savings advertised by some PNG compressors, often 70% or more, come from converting the image to a limited palette, a lossy step. This tool never does that, so it never changes how an image looks, and it also never delivers those savings. Text chunks and the embedded colour profile are not written to the result; no colour conversion is applied before the profile is dropped, so an image in a wide-gamut space such as Adobe RGB or Display P3 can look different afterwards (see how colour profiles work).

Which PNGs get smaller, and which grow

We generated PNGs in several ways and ran each through the tool:

Generated locally; not a benchmark; not a guaranteed result. The pattern is consistent, though. The first two rows were written with no compression at all, so there was a lot to recover. After that, files that were already compressed stay about the same size. The last four grew because the result is always a 32-bit image with an alpha channel: a grayscale, indexed or plain RGB PNG is expanded to that form, and the extra data outweighs what the re-compression saves. If the output is larger than your original, keep the original.

If you need a much smaller PNG

• It is a photograph. PNG stores every pixel exactly, which is expensive for photos. Converting with PNG to JPG or PNG to WebP is what shrinks it, at the cost of some detail. WebP keeps transparency; JPG does not.
• It has more pixels than you need. Reduce the dimensions with the image resizer; the file shrinks roughly with the pixel count.
• It is a logo or diagram with few colours. Reducing the palette is the technique that works. This tool does not do it.

The JPG vs PNG vs WebP guide compares the three formats if you are unsure which to keep.

Accepts PNG (.png). Output is always a PNG with an alpha channel, at the same dimensions. JPG, WebP and other formats are not accepted here. An animated PNG is accepted but only its first frame comes back. Limits: 20 MB per file, 12,000 px per side and 40 megapixels. One file is compressed at a time.

1. Choose a PNG (up to 20 MB). The file is identified by its contents, so a WebP renamed to .png is rejected.
2. Click "Compress PNG".
3. Download the result, named after your original with "-compressed" added. If it is not smaller than the original, keep the original.

• Re-saving a PNG that an export tool or screenshot utility wrote with little or no compression
• Producing a lossless copy of a transparent logo with its colours and alpha untouched
• Stripping text chunks and colour-profile data from a PNG as a side effect of re-saving it

This is a lossless re-save, not an optimiser. It does not reduce colours, so it cannot match the savings of palette-reducing PNG tools. The compression level is fixed and not the maximum. Grayscale, indexed and RGB PNGs are always written back as 32-bit RGBA and can come out much larger. Animated PNGs lose every frame after the first, with no warning. Text chunks and embedded colour profiles are removed.