A PNG that's several megabytes slows down pages and fills up inboxes. The right fix depends on what's in the image. Here are six approaches, in the order worth trying.
1. Resize to the size you actually need
File size grows with the number of pixels. Halving the width and height cuts the pixel count to a quarter, and the file usually shrinks about the same. If an image is displayed at 800 pixels wide, a 4000 pixel original is wasted bytes. Use the resize tool to set the dimensions.
2. Reduce the number of colors
Most PNGs store 16 million possible colors per pixel, but a logo, chart or UI screenshot might use only a few dozen. Converting to an indexed palette of up to 256 colors stores each pixel as a small index, which can shrink flat graphics by more than half with almost no visible change. This is what the compress tool does in "Smaller files" mode. If gradients start to look banded, raise the number of colors or turn on dithering.
3. Switch format for photographs
PNG isn't designed for photos. A photograph converted to JPG or WebP is typically many times smaller than the PNG, with little visible difference at sensible quality settings. Compression tricks on a PNG photo rarely get close.
4. Use WebP when you need transparency
If you have a large transparent PNG, such as a product cutout, lossy WebP keeps the transparency and is usually much smaller. Keep the PNG as your master and publish the WebP.
5. Remove what you don't need
- Unused alpha. If nothing in the image is transparent, a file without an alpha channel is smaller.
- Metadata. Text chunks and embedded color profiles add bytes. They are usually small, but add up across thousands of images.
- 16-bit depth. Unless you're doing professional editing, 8 bits per channel is plenty.
6. Re-encode losslessly
Different PNG encoders produce different file sizes for identical pixels, depending on how well they choose filters and compress. A lossless re-encode can trim a few percent without changing how the image looks. It's a small gain, so do it last, or use it when you can't accept any change.
Which one should you use?
| Your image | Try first |
|---|---|
| Logo, icon, chart, UI screenshot | Reduce colors, then resize if it's still large |
| Photograph | Convert to JPG or WebP |
| Transparent product image | Convert to WebP |
| Huge dimensions for a small slot | Resize |
| Must stay PNG with no changes | Lossless re-encode |
All of these run in your browser with no upload, and the file list shows the size before and after for every file, so you can see what each change buys you.