The short answer
JPG and JPEG are the same file format. Both stand for Joint Photographic Experts Group, the committee that created it. A photo saved as photo.jpg and the same photo saved as photo.jpeg contain identical data, and every app, phone and website opens them the same way.
Why are there two names?
Early versions of Windows and DOS limited file extensions to three letters, so .jpeg became .jpg. Macs and Unix systems had no such limit and kept .jpeg. Both spellings stuck, and today software uses either one. Some cameras and apps write .jpeg, others .jpg, and you will also see .jpe and .jfif for the same format.
Can you rename .jpeg to .jpg?
Yes. Changing the ending from .jpeg to .jpg, or back, does not change the picture or the quality, because nothing inside the file changes. The JPEG to JPG converter does this for a whole batch and lets you shrink the files at the same time.
Do not rename other formats this way. A PNG renamed to .jpg is still a PNG inside, and some programs will refuse it. To change the real format, convert it with a tool such as the PNG to JPG converter.
What really changes image quality
- The quality setting. JPEG is lossy, so lower quality means a smaller file and more lost detail.
- Saving again and again. Each re-save recompresses the image and adds small errors. Keep one original and make copies from it.
- Resizing. Making a photo smaller keeps it sharp. Enlarging it does not add detail.
- Metadata. Camera details and location data add a little size but do not change how the picture looks.
Which one should you use?
Use .jpg unless something asks for .jpeg. It is shorter and every system accepts it. If a form or upload says it only accepts one of the two, rename the file to match. If the file is also too large, run it through the JPEG compressor to reduce its size.
JPG compared with PNG
The real choice is between formats, not spellings. JPG gives small files for photos. PNG keeps every pixel exact and supports transparent backgrounds, which suits screenshots and logos. You can convert in either direction with the JPG to PNG converter.
Frequently asked questions
Is JPG better quality than JPEG?
No. They are the same format, so the quality depends on the quality setting used when the file was saved, not on the three or four letter ending.
Why do some websites reject .jpeg files?
Some older forms check the file ending and only list .jpg. Renaming the file to .jpg fixes it, because the contents are the same.
Does converting JPEG to JPG lose quality?
Renaming does not. If you re-save the image with a tool, a small amount of quality can be lost, so use a high quality setting or just rename the file.
What about .jpe and .jfif files?
They are other endings for the same format. A .jfif file opens as a normal JPEG once you rename it to .jpg, or you can convert it with the JFIF to JPG converter on this site.