A .jfif file is already a JPEG
JFIF stands for JPEG File Interchange Format. It is the standard way JPEG image data is packed into a
file, and nearly every photo ending in .jpg is a JFIF inside. When a file ends in .jfif,
the picture is the same kind of JPEG; only the label is different. Many programs, upload forms and phone
apps look at the label, not the content, and refuse anything that doesn't say .jpg or .jpeg. That is the
whole problem, and it doesn't need a new image to solve it.
So this converter does the least it can. It reads the first bytes of each file. A JPEG always starts with
the same three bytes (FF D8 FF); if they are there, the file is handed back as .jpg with
exactly the same bytes. Same size, same pixels, same camera details. Only files that turn out to be
something else are actually converted.
What re-saving costs: our measurement
Most online JFIF converters decode the picture and write a brand-new JPEG, which is the normal way to convert between real formats. For a file that is already a JPEG, it only adds a second round of compression. We took a 2048 × 1536 phone photo (1.59 MB, with EXIF data), saved it as .jfif and converted it both ways in Chrome 154 on 12 October 2026:
| Method | File size | Difference from the original | EXIF (camera, date, location) |
|---|---|---|---|
| Byte copy (this tool) | 1.59 MB | None: identical bytes | Kept |
| Re-encoded at 92% quality | 1.29 MB | PSNR 39.3 dB | Deleted |
| Re-encoded at 80% quality | 818 KB | PSNR 32.7 dB | Deleted |
At 92% the loss is hard to see on a single pass, but it is real and it adds up every time a picture is re-saved. At 80% the smaller file comes from visibly softer detail. And in both cases the photo loses its date and camera information, which matters if you sort pictures by date or need to show when a photo was taken. If you want a smaller file, compress it on purpose with compress image to a target size after converting.
When renaming is not enough
Renaming photo.jfif to photo.jpg is the same lossless fix, and it works for a
real JPEG. It fails when the file is something else wearing a .jfif name. Some sites send WebP or AVIF
to browsers that can show them, and a misconfigured server or download tool can still give the file a
JPEG-style ending. Rename one of those and you get a .jpg that programs expecting a JPEG reject or show
as broken. This tool checks the signature and converts those files for real, at 92% quality, and tells
you which ones they were. An iPhone HEIC photo with the wrong name is pointed to the
HEIC to JPG converter instead.
Why Windows saves pictures as .jfif
When you save a JPEG from a browser, Windows decides the file ending from a registry value:
HKEY_CLASSES_ROOT\MIME\Database\Content Type\image/jpeg, entry Extension.
On a normal PC it says .jpg; on affected ones it says .jfif, and every saved
JPEG gets that ending. Users have linked the change to Windows updates and to some installed software,
and some report that updates switch it back after it was fixed.
- Press Windows + R, type
regeditand press Enter. - Go to
HKEY_CLASSES_ROOT\MIME\Database\Content Type\image/jpeg. - Double-click Extension and change
.jfifto.jpg. - Restart the browser. New downloads now end in .jpg.
Editing the registry is safe for this one value, but change nothing else there. It only affects new downloads; files you already saved as .jfif still need converting, which is what this page is for.
Location data in the photo
Because the byte copy keeps everything, it also keeps GPS coordinates if the photo has them. The tool reads the EXIF block and warns you when a location is in there. To share the picture without it, run the .jpg through Remove EXIF data, or check what else is stored with the metadata viewer.