Windows sometimes saves downloaded pictures as .jfif, and then half the internet's upload forms pretend the file doesn't exist. The annoying part is that JFIF basically is JPEG, just wearing a file extension nobody recognizes.
This tool decodes the file and writes a standard .jpg locally. Since the formats are siblings, conversion at quality 95+ is visually indistinguishable from the original, it just finally has a name your forms accept.
Loading tool…
This is Convert Image Format preconfigured for this task — open the full tool for every option.
Select one or more images.
Choose the target format; consequences (like losing transparency in JPEG) are shown before converting.
Pick a background color if converting transparency to JPEG.
Convert and download individually or as a ZIP.
Every output is re-decoded to confirm it parses as the target format with the expected dimensions; failures are isolated per file.
JFIF is the container standard that JPEG images have used since the 90s. Most software labels these files .jpg, but some Windows setups pick the older .jfif extension, which trips up upload forms that match on the name.
A tiny amount, since JPEG re-encoding is lossy. At quality 95 the difference isn't visible. The output also carries no EXIF metadata, which for downloaded images is usually a plus.
Technical guidance for choosing settings and reviewing the result.
There is no quality percentage that makes every image exactly 1 MB or 100 KB. A reliable target-size workflow measures real encodes, preserves the best result under the limit, and tells you when resizing is necessary.
8 min read · Reviewed August 2026