Guide
Why PNG files are so large
A screenshot that occupies four megabytes feels wrong next to a photograph of the same size that holds far more detail. It is not a fault. PNG is doing exactly what it was designed to do, and understanding that points straight at the two things that actually shrink one.
Short answer
PNG is lossless: it stores every pixel exactly, so it cannot throw away detail to save space. To make one smaller, either reduce how many distinct colours it stores - which is lossless for what remains and very effective on screenshots - or convert to JPEG or WebP if the image is a photograph.
What PNG is actually doing
PNG compresses by finding patterns and describing them compactly, then storing the result exactly. Nothing is approximated. That is the right design for a screenshot, a logo or a diagram, where a softened edge is immediately visible and a colour shifting by one step can be wrong.
The cost is that PNG has no way to say "this is close enough". A photograph contains millions of subtly different colours and almost no exact repetition, which is the worst possible case: there are few patterns to compress, and PNG will not discard any of it. That is why a photograph saved as PNG can be ten times the size of the same picture as a JPEG.
The two things that work
Both of these are large effects, and which one applies depends on what the image contains.
- Reduce the colour count. A screenshot typically uses a few hundred distinct colours while the file is stored as though it might use sixteen million. Quantising to 256 colours is often invisible on interface screenshots and can cut the file by 60-80%.
- Convert, if it is a photograph. A PNG holding a photograph is in the wrong format. JPEG or WebP will be dramatically smaller with no visible difference.
- Reduce the dimensions. Halving width and height quarters the pixel count. Obvious, and frequently the largest single saving when a screenshot is far larger than it will ever be displayed.
When to keep PNG anyway
Keep it when the image has text, sharp lines, flat colour or transparency. Those are exactly the things lossy compression handles worst, and a smeared screenshot is a worse outcome than a large one.
Keep it when the file is going to be edited again. Every lossy re-save compounds; a lossless master does not.
Common mistakes
Saving photographs as PNG because it sounds higher quality. It is lossless, which is not the same as better-looking. For a photograph the quality difference from a good JPEG is invisible and the size difference is enormous.
Converting a screenshot to JPEG to save space. It works and it looks bad. Reduce the colours instead.
Assuming transparency survives conversion. JPEG has none; transparent areas become white.
Frequently asked questions
- Does compressing a PNG lose quality?
- Reducing the colour count is a real change - colours that were slightly different become the same - but the result is still stored losslessly, and on screenshots and flat artwork the change is usually invisible. It is not the same as JPEG compression, which softens edges everywhere.
- Is WebP better than PNG?
- Usually smaller for the same content, and it supports transparency, with lossless and lossy modes. The reason to stay on PNG is compatibility with something that will not accept WebP - which in 2026 is mostly older software rather than browsers.
- Why is my screenshot bigger than my photograph?
- Because your photograph is a JPEG that discarded most of its data, and your screenshot is a PNG that discarded none. The screenshot contains less visual information and stores it exactly; the photograph contains more and stores an approximation.
Last checked 2026-09. File sizes and platform limits change; where this guide states one, it is what we could verify at that date.