Quick answer
Use JPEG for photographs, PNG for graphics that need crisp edges or transparency, and WebP when you want photo-or-graphic quality at a smaller file size and the destination supports it. Most modern websites are best served by WebP with a JPEG or PNG fallback for older systems.
The reason there is no single winner is that these formats were designed for different jobs. JPEG throws away detail the eye barely notices to keep photos small; PNG keeps every pixel exact, which graphics need but photos do not; WebP can do either, usually smaller than both.
JPEG: built for photographs
JPEG uses lossy compression, meaning it discards some image data to shrink the file. For photos with smooth gradients and lots of colour that trade-off is almost invisible at sensible quality settings, which is why cameras and photo sites default to it.
Its weaknesses show up on the wrong content. JPEG has no transparency, and pushing the quality too low produces blocky artefacts and halos around sharp edges and text. If a logo or screenshot looks muddy, JPEG is usually the cause.
- Great for photos and complex colour
- No transparency support
- Avoid for text, logos, and line art
PNG: built for graphics and transparency
PNG is lossless, so it reproduces every pixel exactly and supports a full alpha channel for transparency. That makes it the right choice for logos, icons, screenshots, diagrams, and anything with hard edges or text.
The cost is size. Used for a photograph, a PNG can be several times larger than the equivalent JPEG or WebP with no visible benefit, so reserve it for graphics rather than photos.
- Lossless and pixel-exact
- Supports transparency
- Large and wasteful for photographs
WebP: the modern all-rounder
WebP supports both lossy and lossless modes plus transparency, and typically produces files 25-35% smaller than a comparable JPEG or PNG. For website performance it is usually the best default today, and it is supported in all current major browsers.
The only real caveat is reach: a few older devices, email clients, and strict upload forms still expect JPEG or PNG. When you are unsure of the destination, keep a JPEG or PNG copy as a fallback.
- Smaller files than JPEG or PNG
- Handles photos and transparency
- Keep a fallback for very old systems