JPEG vs JPG: What's the Difference? (And How to Convert Between Them)

Here's a question I get asked surprisingly often: "What's the difference between JPEG and JPG?" The answer is going to feel anticlimactic: there is no difference. They are literally the same format. But that raises an interesting follow-up: why do two identical formats have different names? And more practically: how do you convert between them when software requires one specific extension? Let's dig in. Why Do JPEG and JPG Both Exist? It goes back to the early days of Windows. When the JPEG format was standardized in 1992 by the Joint Photographic Experts Group (hence "JPEG"), file extensions were supposed to match. But MS-DOS and early Windows had a hard limit of 3 characters for file extensions — the infamous 8.3 filename format. So Windows truncated .jpeg to .jpg. Mac and Unix systems didn't have this restriction, so they kept .jpeg. The result: the same format, two extensions, depending on what OS created the file. Modern Windows supports both, but the legacy lives on in software,