Compress a PNG to 100 KB without losing transparency
100 KB is one of the most common upload limits on the web. Job applications, government and school portals, exam registrations, and membership sites often cap photos, signatures, and logos at 100 KB, and Slack rejects custom emoji over 128 KB. A typical PNG screenshot or logo export is several times that size. This tool brings PNGs under 100 KB while keeping them real PNG files, with transparent backgrounds intact and text and edges sharp.
Everything runs in your browser. Your images are never uploaded.
How to use it
- Choose one or more images, or drop them onto the box. PNG, WebP, GIF, JPG, BMP, and AVIF all work, and every result is a PNG.
- Keep the 100 KB target, pick 50, 128, or 200 KB, or type the exact limit you were given.
- If a form also asks for specific dimensions, like 300 × 80 pixels for a signature, set them under the size options.
- Hold an image to compare it with the original, then download it, or download the whole batch as a ZIP.
Where 100 KB limits show up
| Where | Typical limit | Tip |
|---|---|---|
| Signature uploads on application forms | 10 to 100 KB, often with fixed dimensions | Scan or photograph on white, crop tightly, and choose "Dimensions" so the size stays exact. |
| Photos and ID images on government and exam portals | 50 to 100 KB | If the form accepts JPG, a JPG of a photo will look sharper at the same size. |
| Slack custom emoji | 128 KB, square | Use the 128 KB preset. Transparency is kept, so the emoji sits cleanly on light and dark themes. |
| Email signature logos | No hard limit, but under 100 KB is best | Every email you send carries the image. A smaller logo loads faster and avoids spam filters. |
| Marketplace and store thumbnails | Often 100 KB or less | Small, fast-loading thumbnails help category pages load quickly. |
Requirements change, so always check the limit stated on the form you're filling in.
How a PNG gets under 100 KB
PNG has no quality slider like JPG. Its compression is always lossless, so the only ways to make one smaller are fewer distinct colors or fewer pixels. The tool tries these steps in order and stops as soon as the file fits:
- Lossless first. It re-saves the image with every original color. If that already fits, you get a pixel-perfect file.
- Reduce the colors. A palette PNG with up to 256 colors is often 60 to 80 percent smaller than full color. The tool chooses the 256 colors that best represent your image, including partly transparent ones, so soft edges and shadows survive.
- Resize only if needed. If 256 colors still don't fit, the image is scaled down just enough to reach the target.
Logos, icons, and many screenshots already use 256 colors or fewer, so their palette version is still lossless. The card says "lossless" whenever no pixel changed.
What fits in 100 KB as a PNG?
| Kind of image | Typical result at 100 KB |
|---|---|
| Logo, icon, or signature with transparency | Full size, usually lossless |
| Screenshot of an app or web page | Full size at 256 colors up to about 1,400 px wide, smaller beyond that |
| Chart, diagram, or simple illustration | Full size, with few visible changes |
| Product photo on a transparent background | About 700 to 1,000 px at 256 colors |
| Full photo with no transparency | About 500 to 700 px. Save it as JPG instead if the form allows. |
These are rough figures. The tool encodes and measures every image rather than guessing.
Settings worth knowing
| Setting | What it does | Best for |
|---|---|---|
| Balanced | Full color if it fits, otherwise 256 colors, and resizing only as a last resort | Almost everything |
| Every original color | Never reduces colors, and shrinks the image in pixels until it fits | Brand colors and images you'll edit later |
| Dimensions | Keeps the width and height exact, and reduces colors further if needed | Forms that check pixel size, icons, diagrams |
Dithering smooths gradients after colors are reduced, but adds a fine speckle pattern that takes more space. On Auto it's used only when the image still fits at full size. Turn it off for signatures, screenshots, and text, where it only adds noise.
Frequently asked questions
Will my signature or logo keep its transparent background?
Yes. Transparent areas stay transparent, and partly transparent edges get their own palette colors so they blend smoothly on any background.
The form says "under 100 KB." Will the file definitely pass?
Yes. The tool measures the real file and only reports success when it's at or under your limit. It counts 1 KB as 1,000 bytes by default, the stricter of the two common definitions, so a 100 KB result passes whether a site counts 1,000 or 1,024 bytes per kilobyte.
Are my images uploaded?
No. Everything happens in your browser, which matters for ID photos, signatures, and other personal documents.
My PNG is already under 100 KB. What happens?
It's kept exactly as it is, unless you've set dimensions it doesn't match.
Why did my photo get smaller in pixels?
Photos have far more colors and fine detail than PNG stores efficiently, so at 100 KB a photo has to shrink. If the form accepts JPG, use a JPG compressor instead. A JPG photo stays much larger and sharper at the same file size.
Does it remove metadata?
Yes. The new PNG holds only the image. Text chunks, color profiles, and camera data aren't copied, which also saves a little space.