Compress PNG Files
PNG has no quality slider, so this tool compresses differently: it reduces the number of distinct colours and writes an indexed PNG. Transparency survives, and flat graphics often shrink by 60–80%.
Drop your image here
or
Choose ImageYou can also paste an image with Ctrl+V
Images are processed on your device and never uploaded.
• •
Runs on your device — nothing is uploaded.
Working…
0%
- Original
- Result
- Saved
- Quality
How PNG compression actually works
PNG is lossless. There is no quality dial to turn — every pixel is stored exactly. The only way to make a PNG meaningfully smaller is to give it less to store, and the standard technique is colour quantisation:
- Analyse which colours actually appear in the image.
- Choose a representative palette — 256 colours or fewer.
- Map every pixel to the nearest palette entry, dithering where needed.
- Write an indexed PNG, where each pixel is one byte instead of four.
The alpha channel is preserved throughout, so cut-outs and rounded corners stay clean.
When PNG compression works brilliantly
- Logos, icons, illustrations — few distinct colours to begin with, so a 64- or 128-colour palette is often visually lossless.
- Screenshots of interfaces — large flat regions quantise perfectly.
- Charts and diagrams — same story.
When PNG is the wrong format
Photographs contain tens of thousands of distinct colours, and forcing them into 256 produces visible banding. If your PNG is a photograph:
- with no transparency — convert it to JPG and the file will shrink by 90% or more;
- with transparency — convert it to WebP, which does lossy compression and keeps the alpha channel.
The tool will point this out when it detects a photographic PNG.
Colour count guidance
| Colours | Best for | Typical saving |
|---|---|---|
| 256 | Safe default, most images | 50–70% |
| 128 | Icons, simple illustrations | 60–78% |
| 64 | Flat logos, monochrome art | 70–85% |
| 32 | Very simple shapes only | 80–90% |
Frequently asked questions
Are my images uploaded to your server?
No. The image is decoded, processed and re-encoded by your own browser using the Canvas and Web Worker APIs. There is no upload endpoint for this tool — open your browser's network panel while you use it and you will see no request carrying image data.
Will my transparent background survive?
Yes. The alpha channel is quantised alongside the colours and written into the output PNG. Nothing becomes an opaque white box.
Why did my PNG barely get smaller?
Two common reasons: the image is a photograph with too many distinct colours to quantise cleanly, or it was already optimised. In the first case, converting to JPG or WebP is the real fix.
Is this the same as lossless PNG optimisation?
No. Lossless optimisers such as OxiPNG only reorganise the existing data and typically save 5–15%. Palette reduction is lossy but saves far more, which is what most people actually need.
What happens to my file when I close the tab?
It is gone. The image only ever exists in your browser's memory as an object URL; closing or refreshing the page discards it. Nothing is written to our servers, and nothing is stored on your device unless you download the result.