The right image format can make a file several times smaller with no visible difference, or keep a screenshot sharp where another format would blur its text. Here is how the four common formats differ, and which to pick.
The short answer
| Image | Best choice | Why |
|---|---|---|
| Photo for a website | WebP (or AVIF) | Smallest files at good quality |
| Photo to email, print, or upload anywhere | JPG | Opens everywhere |
| Screenshot, or anything with text | PNG (or lossless WebP) | Keeps every pixel sharp |
| Logo or icon with transparency | SVG if you have it, otherwise PNG or WebP | Sharp at any size, transparent background |
JPG (JPEG)
JPG is made for photos. It saves space by throwing away detail your eye is unlikely to notice, which is called lossy compression. At a quality of 75–85, photos look the same and are a fraction of their original size.
- Strengths: small photos, and every app, website, printer, and phone can open it.
- Weaknesses: no transparency, and sharp edges such as text and line art get smudgy halos. Each time a JPG is edited and saved again, it loses a little more detail.
PNG
PNG is lossless: it stores every pixel exactly. That keeps screenshots, diagrams, and text crisp, and it supports transparency.
- Strengths: exact pixels, transparency, and no further loss when edited and saved again.
- Weaknesses: photos saved as PNG are often several times larger than the same photo as a JPG.
WebP
WebP was designed for the web. It can be lossy like JPG or lossless like PNG, and it supports transparency and animation. Lossy WebP photos are typically a quarter to a third smaller than JPG at similar quality.
- Strengths: smaller than JPG and PNG for most images, with transparency. Every current major browser shows it, including Safari since 2020.
- Weaknesses: some older apps, editors, and upload forms still don't accept it. That's why images saved from websites sometimes need converting.
AVIF
AVIF is the newest of the four. It usually makes the smallest files at a given quality, and supports transparency and HDR.
- Strengths: very small files, especially for photos.
- Weaknesses: slower to create, and many apps can't open it yet. Browsers need to be recent: Chrome, Edge, and Firefox, and Safari 16 or later.
For a website, a common approach is to serve AVIF or WebP, with JPG or PNG as a fallback for the few browsers that need it.
Don't forget the size
Format is only half the story. A photo straight from a phone is often 4,000 pixels wide, but a web page rarely shows images wider than 1,600–2,000 pixels. Resizing to the size you'll actually display often saves more than changing the format.
Converting between formats
The Image Converter & Resizer converts and resizes images in your browser, and shows each file's size before and after, so you can compare formats on your own images. For a single conversion, open the page for it:
PNG to JPG JPG to PNG WebP to JPG WebP to PNG JPG to WebP PNG to WebP AVIF to JPG AVIF to PNG
Converting can't add back detail that's already gone: a JPG saved as PNG keeps the JPG's blur, just in a bigger file. Keep the original if you can, and convert from that.