How to use Compress PNG
- Add one or more PNG images.
- Leave Output format on PNG, which is where this page opens, and set PNG colors. Full color (lossless) keeps every color but rarely shrinks the file.
- Select Compress, compare the reported sizes, then download. A file that could not get smaller comes back unchanged under its original name.
Example: Compress PNG
A PNG screenshot at 1920 by 1080 pixels.
Options
- PNG colors
- Opens on 256 colors, which snaps every pixel to a palette and is what actually shrinks a PNG. Full color (lossless) keeps every color and usually lands at about the same size.
- Quality (%)
- Not used for PNG output. It applies to JPEG and WebP only, so it does nothing while the output stays PNG and the colors are reduced instead.
- No maximum pixel size
- On by default, keeping the original width and height. Turning it off reveals Maximum longest side, which also brings a very large PNG inside the 16 megapixel limit for color reduction.
Supported inputs and limits
Where your input is processed
This tool processes your input in this browser. Your text and files are not uploaded to UseFreeTools. Check this tool's limits for anything it may save on your device.
Why an unchanged PNG is a normal result
PNG is already compressed and lossless, so re-encoding the same pixels tends to land on the same number of bytes. The setting that removes data is the color count: every pixel is snapped to one of 256, 128, 64 or 32 palette entries. Text screenshots, icons and flat graphics survive that because they already use few colors. Photographs and soft gradients need thousands of shades and show banding, so WebP or JPEG serves them better.
Questions about Compress PNG
Why did the PNG come back at the same size?
At Full color the same pixels are compressed the same way, so the file lands on roughly the same bytes. Choose 256 colors or fewer to remove data, reduce the pixel size, or use WebP or JPEG when the image is a photograph.
What happens to transparent areas?
They are kept. The output is still a PNG, so the alpha channel survives the color reduction. Transparency would only be lost if you deliberately switched the output to JPEG.
Will small text in a screenshot stay readable?
Text already uses few colors, so the palette has less to change than it does on a photograph. At 64 or 32 colors the letter edges can still shift, so zoom in on the download at full size before you publish it.
Can I reduce the colors of a very large PNG?
Not at full size. Palette reduction is capped at 16 megapixels so the browser tab stays responsive, so turn off No maximum pixel size and set a longest side of about 4000 pixels, or leave the colors at Full color.
Is the original file changed?
No. The tool writes a new file and your original stays where it is. Keep it until you have checked the result, particularly when the image contains gradients.