MP3 vs AAC vs Opus vs WAV
Updated 2026-09-20
WAV stores audio uncompressed: CD-quality stereo is 1,411 kbit/s, about 10 MB per minute. The other three are lossy codecs that throw away what the ear cannot hear. MP3 (1993) is the oldest and the most widely supported; its patents expired in 2017. AAC (1997) is the successor standardised in MPEG-2 and MPEG-4, sounds better than MP3 at the same bitrate and is the default for Apple, YouTube and most streaming. Opus (2012, IETF RFC 6716) is royalty-free, outperforms both at low bitrates and is what WhatsApp voice notes, Discord and WebRTC calls use.
The practical split is simple: WAV for recording and editing, Opus for voice and real-time audio, AAC for video soundtracks and Apple ecosystems, and MP3 whenever the file must play anywhere at all, including car stereos, old phones and upload forms.
Side by side
| Criterion | MP3 | AAC | Opus | WAV |
|---|---|---|---|---|
| Type | Lossy | Lossy | Lossy | Uncompressed (PCM) |
| Year / standard | 1993, MPEG-1 Layer III | 1997, MPEG-2/4 AAC | 2012, IETF RFC 6716 | 1991, Microsoft/IBM RIFF |
| Bitrate range | 32 to 320 kbit/s | 8 to 529 kbit/s (typically 96 to 256) | 6 to 510 kbit/s | 1,411 kbit/s for 16-bit 44.1 kHz stereo |
| Size per minute (typical) | 1 MB at 128 kbit/s; 2.4 MB at 320 | 0.75 MB at 96 kbit/s; 1.9 MB at 256 | 0.2 MB for voice at 24 kbit/s; 1 MB for music at 128 | 10 MB |
| Quality at low bitrates (voice) | Poor below 64 kbit/s | Good (HE-AAC) down to 32 kbit/s | Best; intelligible speech at 12 kbit/s | Not applicable |
| Latency (calls) | High | Moderate (AAC-LD variant) | Very low (5 to 66 ms) | None |
| Plays everywhere | Yes | Nearly (all modern devices) | Browsers, Android, VLC; patchy on Apple outside Safari | Yes |
| Patents | Expired | Licensed (free for end users) | Royalty-free | None |
| Typical use | Downloads, portals, old devices | Video audio, Apple Music, YouTube | WhatsApp voice notes, calls, streaming | Recording, editing, mastering |
Quality per kilobit
Listening tests consistently rank Opus first, AAC second and MP3 third at any given bitrate, with the gap widening as bitrate falls. At 128 kbit/s all three sound close to transparent for most listeners on most material; at 64 kbit/s MP3 is noticeably dull while Opus and HE-AAC still sound acceptable; at 24 kbit/s only Opus delivers clear speech. That is why messaging apps chose Opus for voice notes: a minute of speech is about 200 KB.
WAV has no quality question, only a size one. It is what recorders and editors produce and what you should keep as a master. Ten megabytes a minute is fine on a disk and hopeless for email or a form upload.
Compatibility is why MP3 survives
MP3 is technically the weakest of the three lossy codecs and still the safest choice for a file that must open somewhere you do not control: a car, a conference room laptop, a school portal, a client who "cannot open the attachment". Every device made in the last 25 years plays it, and its patents have expired, so nothing needs a licence. Converting a WhatsApp OPUS voice note or an iPhone M4A memo to MP3 is the most common reason people reach for an audio converter.
AAC, usually in an .m4a or .mp4 file, is the second safest and is smaller at the same quality. Use it when you know the destination is a modern device or a video file. Opus is right for anything real-time or bandwidth-limited and for web audio in Chrome and Firefox, and wrong for anything that must play on an older iPhone or a Windows Media Player.
Which should I use?
- If you are…Sending an audio file to someone or uploading it to a portalChooseMP3Plays on every device and is accepted by every form; 128 to 192 kbit/s is enough for voice and most music.
- If you are…Keeping the soundtrack of a video (MP4)ChooseAACThe standard audio codec inside MP4 and MOV; better than MP3 at the same size.
- If you are…Voice notes, calls, podcasts where bandwidth mattersChooseOpusClear speech at 16 to 32 kbit/s and the lowest latency of any codec.
- If you are…Recording, editing or mastering audioChooseWAVNo generation loss; convert to a lossy format only for the final delivery copy.
- If you are…Music library on Apple devicesChooseAACNative to iTunes and Apple Music at 256 kbit/s; plays everywhere modern.
Frequently asked questions
What bitrate should I use for MP3?
128 kbit/s for speech and casual listening, 192 for music, 320 if size does not matter. Above 192 most listeners cannot tell the difference on ordinary equipment.
Why can't I play a WhatsApp voice note on my computer?
WhatsApp saves voice notes as Opus in an .opus (or .ogg) file, which Windows Media Player and older Apple software do not open. Convert it to MP3 with the OPUS to MP3 tool; a 5-minute note stays under 5 MB.
Does converting WAV to MP3 lose quality?
Yes, by design: MP3 discards inaudible detail. At 192 kbit/s or above the loss is inaudible to almost everyone. Keep the WAV if you will edit again; converting MP3 back to WAV does not restore what was removed.
Is M4A the same as AAC?
M4A is the file extension for an MP4 container holding only audio, almost always AAC (or ALAC, Apple's lossless codec). "AAC" is the codec; ".aac" files are the raw stream without a container.
Is FLAC better than WAV?
It is the same audio at about half the size: FLAC is lossless compression, like ZIP for audio. It is ideal for archiving; WAV is more universally supported by editing software and hardware recorders.