JPG vs JPEG: there is no difference in the picture. They are two file name endings for one image format, JPEG. A .jpg file and a .jpeg file hold the same kind of data and open in the same programs, and a photo copied from one name to the other matches byte for byte. Only the letters after the dot differ.
- Same format: .jpg and .jpeg both mean a JPEG picture, as do rarer endings such as .jpe and .jfif.
- Same quality: it is set when a JPEG is saved, never by its ending.
- Renaming is safe: .jpeg to .jpg, or back, changes nothing inside the file.
- If you can choose, use .jpg, the more common ending.
Short answer: JPG and JPEG are the same format
The only difference between JPG and JPEG is one letter in the file name. JPEG is the name of the format, after the Joint Photographic Experts Group, the committee that wrote the standard. Microsoft's list of file name extensions gives the two endings one entry, "jpg, jpeg", as a Joint Photographic Experts Group photo file. The Library of Congress format description lists .jpg, .jpeg, .jpe and .jfif, among others, for the same format.
To show it, we saved a photo as photo.jpg and made a copy named photo.jpeg. Both files were 3,853,037 bytes, with the same SHA-256 checksum, a fingerprint that changes if even one byte changes. Both start with the same three bytes, FF D8 FF: the marker our image tools look for to recognise a JPEG, whatever the file is called.
The web treats them as one format too. The IANA register of media types, the official names browsers and servers use for kinds of file, has one entry for JPEG pictures, image/jpeg, and none for image/jpg.
| .jpg | .jpeg | |
|---|---|---|
| Format inside | JPEG | JPEG |
| Media type | image/jpeg | image/jpeg |
| Our test photo | 3,853,037 bytes | 3,853,037 bytes |
| Letters after the dot | 3 | 4 |
| How common | The ending used most often | Less common |
If the choice in front of you is really between JPG and PNG, that is a different question with a real answer: JPG or PNG explains which suits photos and which suits screenshots, logos and see-through backgrounds.
Why there are two extensions
The first JPEG standard dates from 1992. The ITU approved it as Recommendation T.81 on 18 September 1992, and the JPEG committee gives 1992 as the year the standard was created. The format's name has four letters, which did not fit everywhere.
The older MS-DOS FAT file system allowed at most 8 characters for a file's name and 3 for its extension, the "8.3 file name" described in Microsoft's file naming guide. A JPEG saved there had to end in .jpg. Systems without that limit could use the full .jpeg, pictures moved between the two, and both endings stayed in use.
Today's Windows file systems are not limited to 8.3 names, as the same Microsoft guide notes, but .jpg had become the habit, and the Library of Congress still describes it as the JPEG ending used most often.
Does renaming .jpeg to .jpg change anything?
No. Renaming changes the label, not the picture. A photo renamed from holiday.jpeg to holiday.jpg keeps its pixels, size, camera details and quality, and you can rename it back without losing anything.
To change an ending you first need to see it. In Windows 11, File Explorer shows endings once you choose View, Show, File name extensions, as the Microsoft page above explains. On a Mac, choose Finder, Settings, Advanced and select Show all filename extensions (Apple's steps). Then rename the file as usual, and confirm if your computer warns you about changing the extension.
Renaming does not convert a file
Renaming works between .jpg and .jpeg only because they are the same format. Renaming a PNG to .jpg does not make it a JPG. We tried it: a PNG copy of our test photo, renamed to .jpg, still started with the bytes that spell PNG and was still 31,576,925 bytes, about eight times the size of the real JPG. Apple warns that changing a file's extension can leave it unable to open in the app that made it.
A picture that really is a PNG needs converting instead. Convert PNG to JPG makes a true JPEG in your browser, with any transparent areas filled with white, because JPEG cannot store transparency. Our image tools read the first bytes of a file rather than trusting its name, so a mislabelled PNG opens as the PNG it is.
When the difference matters: upload forms that accept only one
The ending matters in one place: a website or form that checks the name of your file. A web form can tell your browser which files to offer, by ending or by media type. MDN's guide to the accept attribute shows a profile picture form that lists .jpg and .jpeg separately, because a form that names endings has to name both. When a form lists only one, a good .jpeg can be greyed out in the file picker, or refused after you choose it.
- Rename the file. If the form wants .jpg and you have .jpeg, or the other way round, change the ending as above.
- Check what the file really is. A renamed file that is still refused may not be a JPEG at all, such as a PNG with a .jpg name: convert it instead.
- Check the size limit as well. To get under one, compress a JPG with a Quality from 1 to 100 or a target size in KB. The result still ends in .jpg.
- Watch capital letters on a website. Microsoft's naming guide warns that some file systems treat OSCAR and oscar as different names, so a link to photo.jpg can miss a file saved as photo.JPG.
On Whatafile the ending never matters on the way in. Our image tools accept files ending in .jpg or .jpeg, and every JPEG they save ends in .jpg, the more common of the two.
Worth knowing
We checked every source linked in this post, and ran the file tests described above, on 22 October 2026.
JPG vs JPEG questions
Is JPG the same as JPEG?
Yes. JPG and JPEG are two endings for one image format. The files hold the same kind of data and open in the same programs; only the name differs.
Should I save as JPG or JPEG?
Either works. If you can choose, use .jpg: it is the more common ending, so you are less likely to have to change it. If a form asks for .jpeg, rename the file to match.
Can I rename a .jpeg file to .jpg?
Yes. Renaming changes only the name; the picture, its size and its quality stay as they were. This works only between .jpg and .jpeg: renaming a PNG to .jpg does not convert it.
Is JPEG better quality than JPG?
No. The ending has nothing to do with quality, which is chosen when the JPEG is saved: in our JPEG compressor, a number from 1 to 100, starting at 75. The same photo saved at the same quality is identical under either ending.
What does JPEG stand for?
Joint Photographic Experts Group, the standards committee behind the format. The committee's about page describes it as a working group of ISO and IEC that also works with the ITU, which approved the first JPEG standard in 1992.