JPG vs JPEG: what’s the difference?

JPEG is named after the Joint Photographic Experts Group, the committee that published the standard in 1992. Early versions of Windows and MS-DOS only allowed three letters after the dot, so Windows programs saved these files as .jpg. Macs and Unix systems had no such limit and used .jpeg. Both stuck, and every program today opens either.

A few rarer spellings mean the same thing too: .jpe, .jif and .jfif. JFIF is the name of the file layout most JPEGs use, and Windows sometimes saves pictures downloaded from the web with that extension.

Some upload forms check the letters after the dot rather than the file itself, so a perfectly good photo.jpeg is refused where photo.jpg would pass. Renaming it is safe: right-click → Rename on Windows, or click the name in Finder on a Mac, and change the ending to .jpg. For a .jfif file, renaming works the same way, or convert JFIF to JPG to be certain.

If renaming doesn’t help, the file probably isn’t a JPEG at all. iPhone photos are often HEIC, and images saved from websites are often WebP, even when they carry a .jpg name. Identify the file to see what it really is, then convert it with HEIC to JPG or the image converter.

JPEG is a lossy format built for photographs: it discards fine detail the eye barely notices, which keeps photos small. That makes it the right choice for photos you send, upload or print, and a poor one for screenshots, text and logos, where it smudges sharp edges — use PNG for those. Every time a JPEG is edited and saved again it loses a little more, so keep an original if you’ll edit it repeatedly.