.jpg File Extension

What kind of file is a .jpg?

A .jpg file is a JPEG-compressed image. It normally uses the image/jpeg MIME type, just like a .jpeg file. The shorter suffix does not change the pixels, compression method, or image quality.¹

JPEG is especially effective for photographs and other images with gradual color changes. It uses lossy compression, so an encoder can discard subtle detail to make the file smaller. Sharp text, diagrams, and flat-color graphics can show ringing or block artifacts at aggressive settings.

How do I open a .jpg on my computer?

JPG is one of the most widely supported image extensions:

• On Windows, open it with Microsoft Photos, Paint, or a web browser. Microsoft describes Photos as its built-in app for viewing, organizing, editing, and sharing images.²
• On macOS, double-click it to use Preview. Preview can also crop, annotate, resize, and export images.³
• On Linux, use the desktop image viewer, GIMP, or a browser.
• On iPhone, iPad, and Android, the standard photo and file apps can display JPG images.

For detailed editing, Adobe Photoshop, Affinity Photo, GIMP, and many other image editors support .jpg.

Poly support for .jpg

Poly gives JPG images thumbnails, an in-app preview, camera metadata when available, visual search, and agent understanding. A photograph can be found by its filename or visual content, and the Poly agent can reason about what appears in it.

Words visible inside an ordinary JPG are not indexed as document text. Also review Exif metadata before publishing a photo. It can contain capture dates, camera details, and GPS coordinates.

History of .jpg

The JPEG standard arrived in 1992, but the .jpg spelling reflects an older filename constraint. MS-DOS FAT filenames used the 8.3 convention, which allowed no more than three characters after the period.⁴ .jpeg was therefore shortened to .jpg for compatibility.

Modern filesystems support longer names, so .jpg and .jpeg now coexist. IANA associates the image/jpeg media type with JPEG images rather than treating the two suffixes as different formats.¹

Working with .jpg and alternatives

JPEG has no universal compression ratio. Results vary with the photograph, encoder, quality setting, and chroma subsampling. In one Google study, WebP produced files 25% to 34% smaller than JPEG at equivalent or slightly better SSIM across its tested datasets and quality levels.⁵

Choose the alternative that matches the job:

• PNG for transparency, screenshots, line art, or lossless pixels.
• WebP or AVIF for smaller modern web images.
• JPEG XL for advanced photographic workflows and reversible recompression of existing JPEG collections.⁶
• TIFF for editing, scanning, or archival workflows where larger files are acceptable.

Converting an existing JPG to a lossless format prevents another lossy save, but it cannot restore detail already discarded by JPEG compression. Keep the best available original when future editing matters.