What is JPG?
JPG (JPEG) is a lossy raster format built for photographs. It shrinks file size by discarding detail the eye is less likely to notice, which makes it a default for cameras, email, and the open web.
JPG (JPEG) is best for photographs and everyday sharing when file size matters. Extensions: .jpg, .jpeg, .jfif. MIME: image/jpeg. Can be used as input. Can be used as output.
Common uses
- Photos and continuous-tone images
- Email and messaging attachments
- Sites that need small download sizes
Things to know
- Does not store an alpha (transparency) channel
- Repeated re-encoding can add blocky compression artifacts
- Poor fit for sharp UI, logos, or text-heavy graphics
- Formatly converts JPG in your browser. Files are not uploaded.
How JPEG actually compresses
JPG is JPEG: a lossy raster. The encoder converts to YCbCr, typically subsamples chroma (often 4:2:0), splits the image into 8×8 DCT blocks, and throws away coefficients according to a quantization table. That is why files get small and why you see block edges on high-contrast type. There is no alpha channel in baseline JPEG. Progressive JPEG still has the same samples; it only changes the decode order.
Formatly decodes JPEG with the browser’s image decoder and can encode JPEG from other formats with the canvas encoder. Quality in the converter is that encoder’s quality, not a magic restoration of optical detail. EXIF, GPS, and ICC profiles from a camera JPEG are not guaranteed to survive a canvas round-trip; use strip options when you do not want location in a public file.
When JPEG is the wrong container
Screenshots, UI, logos, and text belong in PNG or SVG — JPEG ringing around glyphs is not ‘compression you can live with,’ it is damaged type. Anything that needs a hole in the image needs PNG or WebP with alpha. Archival masters that must not lose another generation belong in a lossless format, not another JPEG.
Keep JPEG for photographs, email attachments, and destinations that still name .jpg in a spec. Prefer WebP on modern websites if size is the goal and the client can decode it. Convert HEIC to JPEG when Windows or mail cannot open the iPhone original — that is interchange, not enhancement.
This page does not upload the file
The converter on this format page runs in the browser. Open DevTools → Network, drop a JPEG or export to JPEG: you should not see the image posted to Formatly for conversion. Scripts for the app are not your photo.