The core difference
PNG is always lossless: what you save is exactly what you get back. WebP can be lossy or lossless, so one format covers photo-style and graphic-style needs.
How to choose
- Website graphics and photos with transparency: WebP, usually much smaller than PNG.
- Screenshots with text, pixel art and anything you will edit again: PNG, because nothing is approximated.
- Files you send to other people or upload to unknown systems: PNG is accepted more widely.
- A master copy of artwork: keep PNG and export WebP for delivery.
File size and quality
Lossy WebP is typically much smaller than PNG for photographic content, because PNG cannot discard anything. For flat graphics with few colours, PNG can be competitive, and lossless WebP is often smaller still. The converters on this site show the exact size change for your own files so you do not have to guess.
Compatibility
Current versions of Chrome, Firefox, Safari and Edge display WebP. Some desktop software, older email clients, print services and upload forms do not accept it. PNG is the safer choice when you do not control the destination.