Glossary
Lossy vs Lossless Compression
Also: lossy and lossless · lossless vs lossy
Lossy compression discards image data to shrink files, causing slight quality loss; lossless compression reduces file size with no quality loss by encoding data more efficiently. JPG is lossy; PNG is lossless.
Reviewed by Chad Solomon · Updated June 2026
Explained
What lossy compression does
Lossy compression permanently removes image detail to achieve small files. JPG, WebP, AVIF, and HEIC are lossy. Each time a lossy image is re-saved it loses a little more quality — known as generation loss. Lossy formats suit photographs, where the discarded detail is imperceptible.
Explained
What lossless compression does
Lossless compression rebuilds the image exactly, bit for bit. PNG, GIF, and BMP (uncompressed) are lossless. Files are larger than lossy equivalents but never degrade on re-saving. Lossless formats suit logos, text, screenshots, and master archives.
Explained
Which should you use
Use lossy for photos and lossless for graphics with sharp edges or transparency. WebP is unusual: it offers both a lossy and a lossless mode, so it spans both jobs.
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Questions
Frequently asked
- Is JPG lossy or lossless?
- JPG is lossy. It discards image detail to produce small files, so quality drops slightly each time a JPG is edited and re-saved.
- Is PNG lossy or lossless?
- PNG is lossless. It reduces file size without discarding any image data, so a PNG never loses quality when re-saved.
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