JPG and JPEG are the same format

JPEG is the name of the image standard. JPG is the three-letter file extension left over from the DOS 8.3 limit, which allowed only eight characters plus a three-character extension. Software that still expects three letters writes .jpg. Software that can use four writes .jpeg. Both names point at the same format.

The bytes inside a .jpg file and a .jpeg file are identical when the encoder used the same settings. Renaming one extension to the other does not recompress the picture, strip data, or change how it looks. The JPG format guide covers what those bytes actually store.

The MIME type is image/jpeg either way. Browsers, email clients, and photo apps treat both extensions as the same type. What changes file size and visible quality is the JPEG quality setting, not the extra letter on the name.

On EditItAll, compression runs entirely in your browser. Files are processed right on your device, and the page works offline after it loads. Nothing is uploaded, there is no account, and there is no watermark. Open JPG compress, set the quality slider, and optionally cap the longest side. There is no target-file-size field. The results list shows in → out size, rounded to whole KB, so a readout of 20 KB can be 20.4 KB.

Color subsampling, EXIF metadata, and progressive encoding are choices the encoder makes when it writes the file. They are not properties of the .jpg extension versus the .jpeg extension. A file can use any of those options under either name.

• Do not pick .jpeg because you want sharper color or smaller files. The extension will not do that.
• Do not pick .jpg because you want to drop metadata. Renaming leaves the bytes alone.
• If a program rejects one extension, rename it. The picture stays the same.

If the question is whether a photo should stay a JPEG or become a PNG, that is a format decision, not an extension decision. Photos with smooth tone usually stay JPEG. Graphics with flat color, text, or a transparent background usually belong in PNG. Use PNG to JPG only when you have already chosen JPEG and you are starting from a PNG.

If the question is how small the file should be, change the quality slider on the compress page, not the letters after the dot. Match the setting to how the image will be viewed, then check the rounded KB readout before you download.