Compress PNG to 100KB — Free, Fast & Private
PNG is lossless, so unlike a JPEG it has no quality dial to turn down. A byte limit on a PNG therefore has to be met some other way, and this page explains which way the MiniPx engine takes, and in what order. The tool opens on PNG with the target already at 100 KB, and the output stays a PNG.
What the engine does to a PNG, in order
First it encodes the image losslessly at its current size. If that already fits, you get a lossless file and nothing about the picture has changed. If it does not fit, the engine reduces the number of colours, trying progressively fewer and checking the size after each step. A PNG with a reduced palette is still a PNG, and flat graphics, logos and screenshots often fit because they used few colours to begin with. If reducing colours is still not enough, the engine reduces the pixel dimensions in steps and tries again. The finished file is measured, and a miss is reported as a miss.
Colour reduction is the one lossy step. Choose the keep-colours option in the tool's PNG settings and it is off the table: the engine stays lossless and, when 100 KB cannot be reached that way, says so instead of quietly changing your colours.
What fits in 100 KB — measured on this page
We dropped five real files on the compressor above and kept what it handed back. 2 of 5 came out under 100 KB.
| File | Before | After, on this page | Under 100 KB? |
|---|---|---|---|
| 12 MP phone photo | 4032 × 3024 px · 3.73 MB | 2580 × 1935 px · 1.55 MB | No — 1.55 MB |
| Portrait / headshot | 3264 × 4653 px · 2.25 MB | 2089 × 2978 px · 976.2 KB | No — 976.2 KB |
| Scanned handwritten page | 3349 × 4281 px · 2.17 MB | 2143 × 2740 px · 1.68 MB | No — 1.68 MB |
| Scanned signature | 2041 × 617 px · 109.1 KB | 2041 × 617 px · 50.0 KB | Yes |
| Screenshot (PNG) | 1280 × 800 px · 88.1 KB | 1280 × 800 px · 88.1 KB | Yes |
Measured 2026-10-06 in Chromium 145.0.7632.6 with this page’s own settings. The photos are public-domain and CC0 files from Wikimedia Commons; the screenshot is our own. Sizes read as the tool shows them (1 KB = 1,024 bytes); the target itself is 100,000 bytes, which is under 100 KB on either reading.
What differs from the JPEG route
There is no continuous quality search for PNG, so the result lands wherever the palette step lands, not snugly under the limit. A photograph saved as PNG is the hard case: it uses a great many colours, so a small limit usually costs both colours and pixels, and the table shows what that did to the real photographs we tested. A screenshot or graphic is the easy case. If the form accepts JPG, a JPEG is far smaller for a photograph, and the JPEG page is the better start.
Decimal kilobytes
KB here is 1,000 bytes. A file under that is also under a portal that counts 1,024-byte kilobytes, so the decimal reading is the safe one for either kind of form.