website needs photo in jpg format, not jpeg. how do I change

.jpg and .jpeg are the same so just edit the suffix if the site so insists.

There is basically no difference between those two formats, and they should be compatible.

Way back in the past only 3 letters could be used as an extention for a file.

Did you try to rename the *.jepg into *.jpg?

If this does not work, can you change the format in the app on your Mac Mini, i.e. "save as *.jpg"

lorriefromnc wrote:

my mac mini automatically saves photos to jpeg

Rename the file, as mentioned in replies above.

Some info on the JPEG file formats, including the various file extensions used: https://en.wikipedia.org/wiki/JPEG

Might want to suggest the folks that created the web content management system you’re using here consider reworking thensystem to adapt to the provided image names and formats, too.

One common approach they could use would be to examine the contents of the provided file (the so-called file signature or file magic value), and then name the file per whatever local requirements exist.

macOS and most other UNIX and Linux systems have file format detection tooling built in.