PNG is the format of screenshots, logos, icons, diagrams and anything with a transparent background. It keeps every pixel exactly, which is its strength, and also why PNG files can be surprisingly large.
This PNG compressor makes the file smaller and keeps it a PNG. You choose between two kinds of compression: Lossless, which keeps every pixel and only packs the file better, and Fewer colours, which makes it much smaller by using a limited set of colours. Transparency is kept with both. It all runs in your browser, and nothing is uploaded.
How to compress a PNG
This PNG compressor opens with Format set to PNG and Lossless picked, so a first try needs no settings at all.
- Press Select images and choose your PNG files. You can select up to 100 at once.
- Under Compress by, keep Quality. Under PNG, pick Lossless or Fewer colours.
- With Fewer colours, drag the Colours slider. It runs from 2 to 256 and starts at 128.
- Check the split view and the Original and Result bars, which show the exact sizes once measured.
- Press Compress and save. The file name ends in _compressed.png.
Every result is a PNG unless you change Format. You can open other pictures too, such as a JPG, and they are saved as PNG, but a photo saved as PNG is usually bigger than the JPG it came from. For photos, the Compress JPEG page or WebP is the better route, and JPEG vs PNG sets out when to send each.
To reduce PNG file size for a whole set, such as the screenshots for a guide, select them together. Every file gets the same settings, the button counts them, for example Compress 8 pictures, and Save all as ZIP saves them in one go. The done screen shows each file's new size and how much smaller it is. A PDF does not open here, so convert PDF to PNG first and compress the pages it gives you.
Lossless or Fewer colours: two kinds of PNG compression
The two choices under PNG work in different ways, and the difference in size can be large. Lossless changes nothing in the picture; Fewer colours is lossy, because it changes some pixels. The same split, with JPEG as the lossy example, is explained in lossy vs lossless compression. Try both on your picture: the Result bar updates each time.
Lossless: every pixel kept
Lossless PNG compression keeps the picture exactly as it is. Every pixel, every shade and every bit of transparency stays the same. It works as a PNG optimiser, packing the file tighter without touching a pixel, and it also takes out details that are not part of the picture, such as text notes and dates that apps write into PNG files.
How much you save depends on how the PNG was made. A file from an app that saves quickly can shrink a fair amount; a PNG that was already optimised may get only a little smaller. Either way, nothing about the picture changes. That makes lossless PNG compression the safe way to optimise a PNG that must stay exact, such as a design file or a screenshot of fine print.
Fewer colours: much smaller files
Fewer colours rebuilds the picture with a limited set of colours, the number you set on the Colours slider. A screenshot or a logo rarely uses many colours anyway, so it often looks the same with far fewer, and the file can shrink a great deal.
This one does change pixels. Smooth gradients, soft shadows and photos can show steps or bands when the colours run short. Zoom to 100% and use Hold to compare to check, and raise the Colours if you see bands.
How many colours does your picture need?
The Colours slider starts at 128, which suits most screenshots. These are starting points to try, not rules: drag the slider and watch the result.
| Picture | Try | Why |
|---|---|---|
| A simple logo or icon with flat colours | 16 to 32 | Few colours to begin with; edges need only a few in-between shades |
| A screenshot of an app or a document | 64 to 128 | Text, buttons and plain backgrounds |
| A chart or a diagram | 32 to 64 | Flat fills and lines |
| An illustration with gradients or soft shadows | 128 to 256 | Smooth changes need more shades |
| A photo | Use JPG, WebP or AVIF | Photos need far more colours than a PNG palette holds |
If the picture has a transparent background with soft edges, such as a logo with a shadow, keep the Colours a little higher. The soft edge is made of many shades of see-through colour, and too few of them can make it look rough.
Reduce PNG size to a KB limit, and keep transparency
When a form or a site caps the file size, use this page as a PNG size reducer: switch Compress by to Target size and set the size. For a PNG, the tool tries lossless first, then 256, 128, 64, 32 and 16 colours, and with Allow a smaller picture size on, it then makes the picture smaller in pixels to get under the target. The result is the target or a little under, and a KB here is 1,000 bytes. If no setting gets there, the panel says so and suggests what to change. The compress an image to 50 KB page opens with a 50 KB target already set.
A PNG with transparency stays transparent with Lossless, Fewer colours and Target size alike, so a logo still sits cleanly on any background after you reduce PNG size. The colour profile is kept too, so the colours look as they did. Camera, location and text details are removed.
To make a large PNG smaller in pixels as well, switch on Also make it smaller in pixels and set the Longest side, from 320 to 8,000 pixels. A screenshot from a high-resolution screen can be twice as wide and tall as it needs to be, and halving its sides leaves a quarter of the pixels.
When PNG is not the right format
PNG is made for exact pixels, not for photos. If your PNG is a photo, such as a camera picture someone saved as PNG, no PNG setting will make it as small as a photo format can. Switch Format to another choice:
- WebP keeps transparency and is usually much smaller than PNG for photos and detailed artwork.
- AVIF is often smaller still, and keeps transparency too, but takes longer to make. If you only want the change of format, PNG to AVIF does that.
- JPG opens anywhere, but has no transparency: transparent areas become white.
Keep PNG when the picture must stay pixel-exact, when it is going into another design, or when the place you upload it to asks for PNG. Then Lossless or Fewer colours is the way to compress PNG files without leaving the format. The other ways to make pictures smaller are in the full image compressor.
Compress your PNG now
With this PNG compressor, start with Lossless, which never changes a pixel. If you need the file much smaller, switch to Fewer colours and lower the Colours until you see a change, then step back up. For photos, a photo format will always win.
Select your PNG files above and press Compress. It is free, and nothing is uploaded.
