PNG is a lossless image format. It stores every pixel exactly, so a picture saved as PNG and opened again is identical to the original. It was created in the mid-1990s as a patent-free replacement for GIF, became a W3C recommendation in 1996, and is supported by every browser, operating system and image editor.
How PNG works
Before compressing, PNG runs each row of pixels through a filter that records how each pixel differs from its neighbours. Areas of flat colour then turn into long runs of near-zero values, which the DEFLATE algorithm (the same one used in ZIP files) packs very tightly. This is why screenshots and logos make small PNGs, while photos, where neighbouring pixels rarely match, make big ones.
What PNG is good at
- Sharp graphics. Screenshots, logos, icons, diagrams and text stay crisp with no blurry halos.
- Transparency. PNG has a full alpha channel, so pixels can be fully or partly see-through. Soft shadows and smooth edges look right on any background.
- Repeated editing. Because nothing is lost, you can open and save a PNG any number of times without it degrading.
- High precision. PNG can store 16 bits per channel, useful for scientific images and professional editing.
Where PNG falls short
Photos saved as PNG are large, often three to ten times the size of a JPG that looks the same. For photos on the web, JPG, WebP or AVIF are better. Standard PNG also has no animation; the APNG extension adds it and is supported by modern browsers, but many apps only show the first frame.
PNG compared with other formats
| PNG | JPG | WebP | |
|---|---|---|---|
| Compression | Lossless | Lossy | Lossy or lossless |
| Transparency | Yes | No | Yes |
| Best for | Graphics, screenshots | Photos | Websites |
Common PNG conversions
Convert PNG to JPG to make photos smaller for sharing, or to WebP to make website images lighter while keeping transparency. Convert other formats to PNG when you need a lossless copy for editing or a transparent background.