My image ends in .jpg but the site says the format is not supported. What is going on?
Most likely the file is not a JPEG inside, whatever its name says. The extension is just part of the name, and a strict upload form reads the file's contents. Add the image to the format converter: if its row shows WEBP → JPEG you have found the cause, and the tool rewrites it as a genuine JPEG instead of treating it as one already.
How a WebP ends up named .jpg
There are several routes. Some sites show an image at an address ending in .jpg but send the browser a WebP version, and the browser sometimes saves it under the name in the address. Sometimes a person renames the file by hand, believing a new extension changes the format. And some messaging and downloader apps save images with a fixed extension whatever their real format.
The result is a file called product.jpg that opens happily in your browser, while an upload form that checks contents rejects it with 'unsupported format' or 'corrupt file', which is confusing because the name clearly says jpg.
How to see the real format
Every image format starts with a distinctive run of bytes called a signature. JPEG files start with one; WebP files start with the words RIFF and WEBP. The Image format converter ignores the extension when it takes in a file and reads that signature instead. So each file's row shows its true type followed by the target, such as WEBP → JPEG, even when the name ends in .jpg.
That matters because the tool leaves files that are already in the target format alone. If it went by the name, it would skip your file as already JPEG and the problem would remain. Because it knows the file is WebP, it genuinely converts it.
The fix, step by step
- Add the rejected file to the tool.
- Choose JPEG and leave the quality at 90.
- Read the file's row. If it says WEBP → JPEG and shows a result size, it has been converted. If it says the file is already JPEG and was left unconverted, the format is not your problem.
- Download the result. It keeps the name product.jpg, and your browser may add a number if a file with that name is already in Downloads, so upload the new file, not the old one.
If the file really is JPEG and still gets rejected
If the tool tells you the file is already JPEG, the rejection is about something else, usually size or dimensions. Check the requirements printed near the platform's upload button. Size is a job for the Image compressor, dimensions for the Image resizer. And if the converter itself refuses the file as an unsupported type, it is not JPEG, PNG or WebP at all; it may be HEIC or GIF, which this tool does not read.
Common questions
Can I just rename it to .webp and upload that?
Not if the platform does not accept WebP in the first place. The fix is to rewrite the image in an accepted format.
How do I know the output is a real JPEG?
The tool checks the output's signature before offering it, and never offers a file whose signature does not match the chosen format.