JPEG

A lossy raster format tuned for continuous-tone photographs, trading detail the eye is unlikely to notice for very small files.

JPEG splits an image into 8×8 blocks, transforms each with a discrete cosine transform and quantises the result according to a quality setting. Because quantisation is irreversible, JPEG is lossy and every re-save degrades the picture a little further.

Representation

binary

Compression

DCT, Huffman coding

Lossy

Yes

Transparency

No

Animation

No

Typical size

0.1–5 MB for a camera photo

Limits

65,535 × 65,535 pixels

File signature

FF D8 FF

Open specification

Yes

Introduced

1992

Organisation

Joint Photographic Experts Group / ITU-T

1. 1992ITU-T T.81 published
2. 1994JFIF becomes the de facto container
3. 2000JPEG 2000 released as a separate, less-adopted successor

• Windowsfull
• macOSfull
• Linuxfull
• Androidfull
• iOSfull

Browsers: Chrome, Firefox, Safari, Edge.

Applications: Photoshop, GIMP, Affinity Photo, Microsoft Word, Google Docs.

• Extremely small files for photographs
• Adjustable quality dial from near-lossless to tiny
• Universal support across every device and application

• No transparency channel
• Visible artefacts around text, logos and hard edges
• Generation loss on every re-save

• Camera photos
• Web imagery
• Email attachments

• Export at quality 80–90 for the web; higher rarely looks different
• Keep a lossless master and export JPEGs from it

• Saving screenshots or logos as JPEG, which blurs text
• Repeatedly editing and re-saving the same JPEG

Convert from the highest-quality JPEG you have. Re-encoding an already-compressed JPEG compounds artefacts.

• JPEG to PNG
• JPEG to WEBP
• JPEG to AVIF
• JPEG to PDF
• JPEG to TIFF
• JPEG to BMP
• JPEG to GIF

• Convert to WebP

  WebP delivers the same perceived quality as JPEG at about a third less bandwidth and is supported by every current browser.

  Trade-offs: Encoding is slower than JPEG; Print workflows may still expect JPEG.

  Learn about WebP

Every conclusion below is derived from the structured facts on this page — nothing is written by hand.

• Browser compatibility100/100

  • Because every major browser engine renders it natively.
  • Because at least one shipping browser renders it.

• Operating system compatibility100/100

  • Because Windows, macOS, Linux, Android and iOS all open it without extra software.
  • Because most platforms handle it natively.

• Software compatibility100/100

  • Because a broad range of applications read and write it.
  • Because several mainstream applications support it.

• Web suitability100/100

  • Because browsers render it natively, so no conversion step is needed at request time.
  • Because lossy compression keeps transfer sizes and Core Web Vitals in check.
  • Because the specification is open, so tooling and CDNs implement it freely.

• Cloud compatibility100/100

  • Because an open specification means cloud SDKs can implement it without licensing friction.
  • Because it converts into many other formats, which suits automated pipelines.

• Everyday consumer usage100/100

  • Because it opens by double-clicking on every mainstream device.
  • Because small files are easy to email, message and upload.
  • Because it is a current format that people and services still expect.

• Metadata support100/100

  • Because it carries EXIF-style embedded metadata.
  • Because it embeds colour-profile metadata.

• Open standards100/100

  • Because the specification is published openly.
  • Because an official specification document is publicly reachable.

• Licensing100/100

  • Because an openly specified format can be implemented without a licence negotiation.
  • Because the core patents are old enough to have expired.

• Popularity100/100

  • Because it sits at the centre of the format ecosystem, with many documented relationships.
  • Because mainstream applications ship support for it.
  • Because every mainstream operating system handles it.

• Decode performance100/100

  • Because smaller payloads mean less I/O and faster first paint.
  • Because mature formats benefit from hardware and SIMD-optimised decoders.

• Compression efficiency69/100

  • Because it compresses lossily, which produces much smaller files than lossless coding.
  • Because it defines a documented compression scheme.

• Transparency0/100

  • Because it has no transparency, so transparent areas are flattened onto a solid colour.
  • Because it has no alpha channel, so edges cannot fade smoothly.

• Animation0/100

  • Because it is a single-frame format and cannot animate.

• Image quality33/100

  • Because it discards detail during encoding, and every re-save compounds the loss.

• JPEG → WebP

  Transparency improves by 100 points because it supports transparency.

  Trade-off: Licensing drops by 33 points because it does not satisfy: the core patents are old enough to have expired.

  Convert JPEG to WebP