PNG Compressor: Reduce PNG File Size Online

PNG is a lossless format, so simply "saving at lower quality" does not exist for it. This PNG Compressor uses the technique made popular by TinyPNG instead: it reduces the image to a smaller colour palette and writes an indexed PNG, which is often dramatically smaller than the original 24- or 32-bit file. Transparency, including soft semi-transparent edges, is preserved, and the output is still a normal PNG that opens everywhere.

The preset starts at 85%, which means a palette of 256 colours. If the palette version would come out larger than a plain lossless PNG, which can happen with some photos, the tool automatically keeps the smaller lossless file, so you never end up with a bigger image than necessary.

How to use it, step by step

1. Drop PNG images onto the upload area, click it to pick files, or paste an image with Ctrl+V. You can add several files at once.
2. Read the note under the slider: it shows how many colours are used. 85 to 99% means 256 colours, 70 to 84% means 128, 50 to 69% means 64, 30 to 49% means 32 and anything lower means 16. At 100% the PNG is saved losslessly.
3. Zoom into gradients and shadows with the before/after slider. If you see banding, move the slider up a step; if it looks the same, try a step lower for an even smaller file.
4. For strict limits choose Target size: the tool tries 256, 128, 64, 32 and 16 colours in turn and, if even 16 colours are too big, scales the image down.
5. Compare the result with the before/after slider and check the size badge, then click Download, or Download all (ZIP) when you processed several images.

Which PNGs compress best

Logos, icons, UI screenshots, diagrams, charts and flat illustrations have relatively few distinct colours, so they often lose most of their weight with no visible change. Photos saved as PNG are the opposite case: they contain hundreds of thousands of colours and stay large even after quantisation. For those, switch the Format to JPG or WebP, or use PNG to JPG when you do not need transparency.

Good to know

• Transparent backgrounds stay transparent; no white box is added.
• The palette is applied without dithering, so smooth gradients are where banding shows first. Keep those at 256 colours.
• If you specifically want a small-palette PNG8 file, the PNG8 converter starts from a 128-colour palette and also accepts JPG, GIF and BMP.
• For the smallest transparent images on modern websites, PNG to WebP is worth comparing.

Private, free and instant

Everything runs inside your browser: images are decoded, re-encoded and zipped on your own device and never uploaded, with no sign-up and no watermark. The dimensions stay untouched unless you enable Resize, EXIF and text chunks are not carried over, and each file can be up to 80 MB.