Why are PNG files so big?
PNG is a lossless format: it keeps every pixel exactly as it is. That is perfect for screenshots, logos, icons, diagrams and anything with sharp edges, text or transparent areas. The downside is size. A full-screen screenshot can easily weigh 1 to 3 MB, and a photo saved as PNG can be five times heavier than the same photo in JPG.
Many PNGs are also saved without much optimisation. The program that created them chose speed over size, or stored millions of colours where a few hundred would look the same. That leaves a lot of room for improvement.
Two ways Plume reduces PNG size
1. Colour-palette reduction (lossy)
A standard PNG can store more than 16 million colours. Most graphics and screenshots use far fewer. Plume can convert the image to a palette of up to 256 carefully chosen colours, the same approach popularised by TinyPNG. The file often becomes 60 to 80% smaller, and for logos, interfaces and illustrations the difference is very hard to see. Transparency is preserved.
2. Lossless optimisation (OxiPNG)
After that, or on its own if you choose a lossless setting, Plume runs OxiPNG. It tries different ways of packing the same pixels and keeps the smallest. Not a single pixel changes. The gain is smaller, often 5 to 30%, but it is completely free in terms of quality.
Choose the lossless option for technical images where every pixel matters, such as pixel art or images you will edit again. For everything else, the lossy preset gives much bigger savings.
PNG or JPG: which one should you use?
A quick rule of thumb:
- Keep PNG for screenshots, logos, text, diagrams, and any image with a transparent background.
- Switch to JPG for photos. A photo in PNG is almost always much heavier than it needs to be. Use PNG to JPG for that, knowing that transparent areas will become white.
- Consider WebP for websites: it supports transparency and is usually lighter than both. Try JPG to WebP, which also accepts PNG files.
If you are not sure, compress the PNG first and look at the new size. If it is still large and the image is a photo, a JPG will probably be far smaller.
Compress PNG screenshots for documents, e-mails and websites
Screenshots pile up quickly in reports, tutorials, support tickets and presentations. Compressing them keeps your documents light and your e-mails under the usual 20 to 25 MB attachment limit. On a website, lighter PNG icons and illustrations help pages load faster, especially on mobile.
If your screenshots are already inside a Word or PowerPoint file, you do not need to extract them: compress the Word document or the presentation directly.
Safe, free and without limits
Screenshots often show private things: e-mails, bank pages, conversations. Unlike most online tools that upload your files, Plume compresses PNGs inside your browser. Nothing is sent to a server, and the tool keeps working offline once the page is loaded.
You can drop as many files as you like, with no account, no watermark and no daily limit, and download them all as a ZIP. Very large images depend only on your device’s memory.
Tips for even lighter PNG files
A few habits make a real difference before you even compress:
- Crop your screenshots. Capture only the window or the area you need, not the whole screen. Fewer pixels means a lighter file.
- Avoid “retina” size when it is not needed. On recent laptops, screenshots are often twice the width of what you see. If the image will be shown small, set a maximum width in Plume.
- Do not save photos as PNG. If the image is a photo, JPG or WebP will be far lighter.
- Keep your originals. If you may edit a graphic again later, keep the uncompressed file and share the compressed copy.
Combined with colour reduction, these simple steps often turn a 2 MB screenshot into a file of a few hundred KB.