I added a JPG and chose JPEG to make it smaller. Why did the converter leave it unchanged?
Because the format converter's job is changing formats, and your image is already JPEG, so it leaves it as it is and shows a note instead of re-encoding it for nothing. To make a JPG smaller and keep it a JPG, use the image compressor, which re-encodes JPEGs at the quality you pick and shows how much you saved.
What you see on screen
After adding the image and choosing JPEG, the file's row shows a note saying the file is already JPEG, so it was left unconverted. That row gets no download button and no result size, and the summary line under the list counts it as left as is. If every image in the batch is JPEG, the Download all button never appears, because there is no new file to download.
This is not a glitch. In the Image format converter logic, when the source format equals the target, the decision is to skip the file, and it never reaches the encoder. The tool reads the format from the file's contents, not its extension, so photo.jpeg is treated exactly like photo.jpg.
Why doesn't it compress the file, since I set a quality?
Because the quality slider here applies to files that are actually being converted. If the tool re-encoded every JPEG it received, anyone converting a mixed batch would lose some quality on their JPEGs without asking for it, and those files might even grow if they were already well compressed. Keeping the two jobs apart means each tool does what you expect: the converter does not touch what is already right, and the compressor re-encodes on purpose.
The right way to shrink a JPG
- Open the Image compressor and add the same image.
- Choose JPEG as the output and start at quality 80.
- Check the size before and after, and the preview. If you need it smaller, lower the quality step by step.
- Download the result. Its name gets compressed added so it does not get mixed up with the original.
If it is still too big after compressing
Most large images are large because of their dimensions. A photo from a recent phone can be over 4000 pixels wide, while a product page shows it in a much smaller space. Reducing the dimensions in the Image resizer first and then compressing saves more than lowering quality alone, and keeps the picture sharp.
So when does the converter help with JPGs?
When you want another format: WebP for a site that accepts it and a lighter file, or PNG for a program that requires it or a working copy you will edit repeatedly. In those cases the JPG really is converted, and it gets a size and a download button.
Common questions
My image is named .jpg but the tool converted it. Why?
Because its contents are not JPEG; it is usually WebP or PNG under the wrong name. The file's row shows its real format.
Can I force the tool to re-encode?
No. The right tool for that is the compressor.