Compress a PNG to 100 KB: what works and what does not

PNG compression is not like JPG compression, and the difference matters more when you are trying to hit a small target like 100 KB. PNG is lossless by default, which means the encoder is reorganizing the file, not throwing away pixels. So if your PNG is a screenshot, a logo, an icon, or any image with flat colors and sharp edges, 100 KB is usually easy to reach. If your PNG is a photograph that somebody saved in the wrong format, 100 KB is going to be a fight you will probably lose.

This post walks through the realistic path to a 100 KB PNG, why the format behaves the way it does, and when you should just give up and convert to JPG or WebP instead.

The fast way

1. Take a look at your PNG first. Is it a screenshot, a diagram, a logo, or an illustration with mostly flat colors? It will compress well. Is it a photo somebody exported as PNG because they did not know better? It probably will not.
2. Open the Compress PNG to 100 KB tool. Drag your file onto the drop area. Like all our tools, nothing uploads; everything runs in your browser.
3. The tool runs a lossless PNG optimization pass and reports the final size. Screenshots and graphics usually land well under 100 KB. If yours does not, the tool will tell you how close it got.
4. If you are under 100 KB, download and you are done. If you are not, and the image is photographic, your best move is to switch formats. The Compress JPG to 100 KB tool will reach 100 KB on a photo with far better visual quality than any PNG ever can.
5. If you need a PNG but do not have a specific size target, the general PNG compressor gives you the cleanest lossless pass without fighting for a ceiling.

How it works

Our PNG compression runs entirely in your browser via WebAssembly. We use a client-side encoder to re-pack the PNG, which does not touch the pixels themselves but finds a more efficient way to store them. For flat-color graphics this is often enough to cut the size in half, sometimes more. For photos, the savings are usually modest; PNG simply is not designed for that kind of data.

Because the compression is lossless, transparency, color profiles, and every pixel stay exactly as they were. That is the whole point of PNG, and it is also the reason you cannot just dial the quality down to hit a target the way you can with JPG. There is no quality knob on a lossless codec.

When it will not work

If your PNG is actually a photograph, reaching 100 KB losslessly is usually impossible at full dimensions. A 1920 by 1080 photo as PNG is often 3 to 5 MB, and the best lossless re-packing might bring it down to 2 to 3 MB. That is still nowhere near 100 KB. No tool can fix that with PNG as the output format, because the format itself refuses to discard information.

The honest fix in this case is to convert. JPG will reach 100 KB on the same photo with quality that looks basically identical to the source. WebP will do the same, often even smaller. Use the right tool for the content: PNG for graphics, JPG or WebP for photographs.

If the form you are uploading to genuinely requires a PNG (some older government systems do), your remaining options are to resize the image smaller before compressing, or to accept that the result will have visible quality loss because some PNG tools will silently convert to an 8 bit palette to hit aggressive targets.

Frequently asked questions

Why does my PNG barely get smaller?

Most likely because it is a photograph. PNG stores every pixel exactly, and photographs contain millions of subtly different pixel values, which do not compress well. Screenshots of text, on the other hand, have huge runs of identical pixels and compress beautifully. If your PNG is a photo, converting to JPG is not a compromise; it is the right call.

Will compression break transparency in my PNG?

Not with a lossless pass. Alpha channels, semi-transparent pixels, and edge anti-aliasing all survive intact. If you need heavy compression and do not need transparency at all, converting to JPG will strip the alpha channel and give you much smaller files, which may or may not be what you want.

Is PNG ever the right choice for a photo?

Rarely. PNG makes sense for photographs only when you need perfectly preserved pixels (for further editing, scientific use, or print) and the file size genuinely does not matter. For any web, email, or upload use, JPG or WebP is almost always the better call.

Ready to compress?

If your PNG is a screenshot or graphic, compress your PNG to 100 KB. If it is a photograph, save yourself the trouble and use the JPG to 100 KB tool instead.