JPG, also written JPEG, is the most widely used format for photos. The name comes from the Joint Photographic Experts Group, the committee that published the standard in 1992. .jpg and .jpeg are the same format; the three-letter version dates from older Windows systems that limited file extensions to three characters.
How JPEG compression works
JPEG splits an image into 8 × 8 pixel blocks and describes each block as a mix of smooth patterns, using a technique called the discrete cosine transform. It then rounds away the fine patterns the human eye is least sensitive to, and stores colour at lower detail than brightness. The quality setting decides how much is rounded away. That’s why JPG files are small, and also why heavy compression shows as blocky squares and smudges around sharp edges.
What JPG is good at
- Photos. Natural scenes, faces and gradients compress very well.
- Compatibility. Every device, browser, camera, printer and app can open a JPG.
- Adjustable size. A quality setting trades file size against detail.
Where JPG falls short
- No transparency. Every pixel is solid, so cut-out logos get a background box.
- Text and graphics. Sharp edges pick up visible artefacts.
- Generation loss. Each time a JPG is edited and saved again, it is compressed again and loses a little more detail.
- Efficiency. Newer formats such as WebP and AVIF produce smaller files at the same quality.
EXIF data in JPG files
Photos from phones and cameras store EXIF metadata inside the JPG: camera model, settings, date and often GPS location. Be aware of this before posting photos publicly. Converting a JPG with xconverter writes a new file from the pixels only, so this metadata is removed.
Common JPG conversions
Convert JPG to WebP to make website images smaller, or to PNG for a lossless copy before editing. Convert HEIC, WebP, AVIF and PNG images to JPG when an app or upload form needs the most compatible format.