Why Windows saves your JPEGs as .jfif, and the one registry value that fixes it

When you right-click an image in Chrome or Edge and select "Save image as," Windows often names the file with the .jfif extension. This can cause issues when uploading to certain websites, portals, or older applications that don't recognize the .jfif file type. However, the file itself is completely intact. The reason behind this lies in Windows' handling of image/jpeg files.

JFIF (JPEG File Interchange Format) is a wrapper used by .jpg files. Both .jfif and .jpg files start with the same bytes (FF D8 FF E0) followed by a few more bytes containing the letters JFIF. Therefore, renaming a .jfif file to .jpg is sufficient to make it work in most cases. No conversion or loss of quality occurs.

The browser's choice of .jfif as the default file extension for image/jpeg files is determined by the Windows registry. Specifically, the value named Extension under the path HKEY_CLASSES_ROOT\MIME\Database\Content Type\image/jpeg holds the answer. On many machines, this value is set to .jfif due to an app or update modifying it. To check yours, open PowerShell as an administrator and run "reg query HKCR\MIME\Database\Content Type\image/jpeg /v Extension."

The fix to change the default file extension from .jfif to .jpg is to modify the registry value. Open PowerShell as an administrator and run "reg add HKLM\SOFTWARE\Classes\MIME\Database\Content Type\image/jpeg /v Extension /t REG_SZ /d .jpg /f." Close and reopen your browser, and the save option will now offer .jpg files.

If you cannot change the registry, renaming each file manually still works. Use PowerShell for a folder full of .jfif files with the command "Get-ChildItem *.jfif | Rename-Item -NewName { $_.BaseName + .jpg }." Only the file names change, preserving the image quality and content.

For phones or instances where you only need to fix a few files without a terminal, a small free tool called "JFIF to JPG" is available. It changes the .jfif extension to .jpg without resaving the picture, retaining all quality. Importantly, it works without an account.