The short answer
They are the same image. JFIF is a container specification for JPEG data; .jpg is the extension nearly everything expects for that data. Convert JFIF to JPG for compatibility, not for quality — there is no quality difference to gain.
What we compared
We took a single 3,024 × 4,032 photograph and exported it twice from the same encoder at the same quality setting — once written with a JFIF APP0 header, once as a plain .jpg. Then we compared the files directly.
| Measurement | .jfif | .jpg |
|---|---|---|
| Entropy-coded scan data | Byte-identical | |
| Decoded pixel values | Identical — zero differing pixels | |
| Header overhead | 18 bytes (APP0) | 0–18 bytes |
| MIME type | image/jpeg | |
| Opens in browsers | Yes | |
| Accepted by upload forms | Often rejected | Accepted |
| Recognised by photo kiosks | Usually not | Yes |
The only measurable difference in the file itself is 18 bytes of header. Everything else that matters is downstream: what other software is willing to do with it.
Where the difference actually bites
- Upload forms. Most validate
accept=".jpg,.jpeg,.png"and reject.jfifbefore a byte is read. - Print services. Kiosk and lab software filters by extension and will not list the file.
- Mobile galleries. iOS Photos and Google Photos skip
.jfifduring media scans. - Older editors. Photoshop before CC 2015 and Lightroom Classic will not import it.
- Email previews. Many clients show a generic attachment icon instead of a thumbnail.
One real technical difference: metadata
A file written with a JFIF APP0 header typically carries no Exif block. That means no camera model, no timestamp, and — importantly — no GPS coordinates. A .jpg straight off a phone usually carries all of it.
So a JFIF saved by your browser is, incidentally, more private than the original photo it came from. If you convert JFIF to JPG here, nothing is added back: the converter copies the compressed data and does not invent metadata.
Which should you keep?
Keep .jpg. It is the same image with wider support and no downside. There is no scenario where holding a file as .jfif gives you an advantage, unless a specific system demands it — in which case our JPG to JFIF converter handles the round trip.
And do not convert to PNG hoping to "restore" quality. JFIF to PNG is the right move only when you plan to edit the image repeatedly; it will not undo compression that has already happened.