Lossy vs Lossless
Lossy and lossless describe two approaches to compression used across images, audio, and video. Lossy compression permanently discards data to achieve much smaller files. Lossless compression shrinks files without losing any information, so the original can be perfectly restored.
Use lossy compression (JPG, MP3, MP4) when small file size matters more than perfect fidelity — most photos, music, and video. Use lossless compression (PNG, FLAC, ZIP) when you must preserve every detail, such as graphics, master recordings, editing, and archiving.
Lossy vs Lossless: side-by-side comparison
| Attribute | Lossy | Lossless |
|---|---|---|
| Data preserved | No (some permanently discarded) | Yes (all preserved) |
| File size | Much smaller | Larger |
| Quality | Reduced (often imperceptibly) | Identical to original |
| Reversible | No | Yes (perfect restore) |
| Examples | JPG, MP3, AAC, MP4 | PNG, FLAC, ZIP, WAV |
| Best for | Delivery, streaming, sharing | Editing, archiving, graphics |
What is Lossy and what is Lossless?
Lossy
Lossy compression analyses content and permanently removes data the human eye or ear is least likely to notice. This yields dramatically smaller files, which is why JPG, MP3, AAC, and most video use it. The trade-off is that quality degrades and each re-encode loses more.
Lossless
Lossless compression reduces file size by encoding data more efficiently, with zero information lost — the original can be reconstructed exactly. PNG, FLAC, and ZIP are lossless. Files are larger than lossy equivalents but suffer no quality loss, even after repeated saves.
When to use which
Choose Lossy
Choose lossy formats for final delivery — web photos, streaming music, and video — where small size and fast loading outweigh perfect fidelity.
Choose Lossless
Choose lossless formats for editing, mastering, archiving, and graphics with sharp edges or transparency, where every bit of detail must survive.
Convert between these formats
Use our free, browser-based converters: