Audio Formats Explained: MP3, AAC, FLAC, WAV & More
· 10 min read
Lossy vs Lossless Audio
Audio compression falls into two categories. Lossy compression (MP3, AAC, OGG) permanently removes audio data that is theoretically less audible to human ears. Lossless compression (FLAC, ALAC, WAV) preserves every bit of the original recording.
| Aspect | Lossy | Lossless |
|---|---|---|
| File size (per minute) | 1-2 MB | 10-30 MB |
| Quality loss | Some (inaudible at high bitrates) | None |
| Best for | Streaming, portable devices, sharing | Archiving, audiophile listening, editing |
| Can convert back? | No (data is permanently removed) | Yes (can convert to any format) |
The practical difference: most people cannot distinguish 320 kbps MP3 from FLAC in a blind test on consumer headphones. Lossless matters for archiving (you can always convert down later) and professional audio work.
Audio Format Comparison
| Format | Type | Typical Bitrate | Quality | Compatibility |
|---|---|---|---|---|
| MP3 | Lossy | 128-320 kbps | Good at 256+ | Universal |
| AAC | Lossy | 128-256 kbps | Better than MP3 at same bitrate | Apple, browsers, Android |
| OGG Vorbis | Lossy | 96-320 kbps | Similar to AAC | Android, Linux, Spotify |
| Opus | Lossy | 64-256 kbps | Best lossy codec | WebRTC, Discord, browsers |
| FLAC | Lossless | 800-1400 kbps | Perfect | Most players, not Apple natively |
| ALAC | Lossless | 800-1400 kbps | Perfect | Apple ecosystem |
| WAV | Uncompressed | 1411 kbps (CD) | Perfect | Universal |
| AIFF | Uncompressed | 1411 kbps | Perfect | Apple, pro audio |
Use our Audio Converter to convert between any of these formats in your browser.
Bitrate and Quality
| MP3 Bitrate | Quality | File Size (4 min song) | Use Case |
|---|---|---|---|
| 128 kbps | Acceptable | ~3.8 MB | Background music, podcasts |
| 192 kbps | Good | ~5.8 MB | Casual listening |
| 256 kbps | Very good | ~7.7 MB | Most listeners can't tell from CD |
| 320 kbps | Excellent | ~9.6 MB | Maximum MP3 quality |
| FLAC | Perfect | ~25-35 MB | Archiving, audiophile |
For podcasts and speech, 96-128 kbps is sufficient. For music, 192 kbps is the minimum for enjoyable listening. 256+ kbps is indistinguishable from lossless for most people.
When to Use Each Format
| Scenario | Recommended Format | Why |
|---|---|---|
| Music archive/backup | FLAC | Lossless, can convert to anything later |
| Sharing music | MP3 320 kbps | Universal compatibility |
| Podcast distribution | MP3 128 kbps | Small files, speech doesn't need high bitrate |
| Web audio | Opus or AAC | Best quality per byte, browser support |
| iPhone/iPad | AAC or ALAC | Native Apple support |
| Ringtone | MP3 or M4R (iPhone) | Device compatibility |
| Professional editing | WAV or AIFF | Uncompressed, no decoding artifacts |
Create ringtones with our Ringtone Maker or trim audio with Audio Cutter.
Converting Audio with FFmpeg
# MP3 to FLAC (lossless from lossy — preserves quality, doesn't improve it)
ffmpeg -i input.mp3 output.flac
# FLAC to MP3 320kbps
ffmpeg -i input.flac -c:a libmp3lame -b:a 320k output.mp3
# WAV to AAC
ffmpeg -i input.wav -c:a aac -b:a 256k output.m4a
# Convert to Opus (best lossy codec)
ffmpeg -i input.flac -c:a libopus -b:a 128k output.opus
# Trim audio (no re-encoding)
ffmpeg -i input.mp3 -ss 00:00:30 -to 00:01:30 -c copy trimmed.mp3
# Merge multiple audio files
ffmpeg -i "concat:file1.mp3|file2.mp3" -c copy merged.mp3Frequently Asked Questions
Is FLAC better than MP3?
FLAC is lossless (perfect quality) while MP3 is lossy. However, at 256+ kbps, most people cannot hear the difference on consumer equipment. FLAC is better for archiving because you can always convert down to MP3 later.
What is the best audio format for quality?
For perfect quality: FLAC or WAV. For best quality-to-size ratio: Opus at 128 kbps or AAC at 256 kbps. For universal compatibility: MP3 at 320 kbps.
Does converting MP3 to FLAC improve quality?
No. Converting lossy to lossless just wraps the already-degraded audio in a lossless container. The lost data cannot be recovered. Always keep the original lossless source if quality matters.
What bitrate should I use for podcasts?
128 kbps MP3 mono is the standard for speech podcasts. 64 kbps Opus sounds equivalent. Music podcasts benefit from 192 kbps stereo.
Why are my FLAC files so large?
FLAC is lossless — it preserves every bit of audio data. A CD-quality track (44.1 kHz, 16-bit, stereo) is about 10 MB per minute in FLAC vs 1 MB per minute in 128 kbps MP3.