MP3 vs WAV vs AAC: What's Actually the Difference?
Every audio format answers one trade-off: quality versus file size. Once you understand the two families, every "which format should I use?" question answers itself.
Lossless formats keep every sample of the original signal. WAV stores it raw; FLAC compresses it like a ZIP file — smaller, but bit-for-bit identical when decoded. Nothing is ever thrown away.
Lossy formats (MP3, AAC, OGG/Opus) shrink files 5–10× further by permanently discarding audio data your ears are least likely to miss — masked frequencies, inaudible detail. Done well, at a decent bitrate, most listeners can't tell. But the discarded data is gone forever, which has a practical consequence we'll get to.
A Quick Tour of the Formats That Matter
WAV — raw, uncompressed PCM audio. Universal, zero decoding overhead, and enormous: about 600 MB per hour of stereo CD-quality audio. This is the format for recording and editing, not for distribution.
FLAC — lossless compression, typically 40–60% of WAV size, perfect fidelity. The archival format: master recordings, music libraries, anything you might re-edit later.
MP3 — the veteran. Not the most efficient codec anymore, but it plays on everything made in the last 25 years. At 128–320 kbps it ranges from acceptable to transparent. Still the default distribution format for podcasts precisely because compatibility beats efficiency there.
AAC / M4A — MP3's successor: noticeably better quality at the same bitrate (a 128 kbps AAC roughly matches a 160–192 kbps MP3). Native across the Apple ecosystem, YouTube, and streaming services. M4A is simply AAC in an MP4 container.
OGG Vorbis / Opus — the open-source champions. Opus in particular is the best quality-per-bit codec in common use: excellent speech at 24–32 kbps, transparent music around 128 kbps. It powers WhatsApp voice notes, Discord, and most real-time streaming. Weak spot: patchy support in older car stereos and legacy devices.
The Comparison Table
| Format | Compression | Quality | Size for 1h stereo | Best for |
|---|---|---|---|---|
| WAV | None | Perfect | ~600 MB | Recording, editing |
| FLAC | Lossless | Perfect | ~250–350 MB | Archiving, music libraries |
| MP3 (192 kbps) | Lossy | Very good | ~85 MB | Universal distribution |
| AAC (128 kbps) | Lossy | Very good | ~58 MB | Apple ecosystem, video |
| Opus (96 kbps) | Lossy | Very good | ~43 MB | Streaming, voice, VoIP |
| Opus (32 kbps, speech) | Lossy | Good (voice) | ~14 MB | Voice notes, low bandwidth |
Converting between any of these takes seconds in an Audio Converter — drag in a file, pick the target format and bitrate, done, right in your browser.
What Bitrate Should You Use for Voice vs Music?
Bitrate is how much data per second the encoder may spend — the main quality dial for lossy formats.
- Voice/podcast (MP3): 96 kbps mono is clean; 128 kbps is the safe standard. The mono-vs-stereo debate is easy to settle: a single voice gains nothing from stereo, and mono spends your entire bit budget on one channel — so 96 kbps mono can sound better than 128 kbps stereo. Use stereo only if music or spatial elements matter to your show.
- Music (MP3): 192 kbps minimum, 256–320 kbps for transparency.
- AAC/Opus: subtract roughly 25–30% from the MP3 numbers for equivalent quality.
Practical presets:
Podcast, voice only ......... MP3 96–112 kbps mono
Podcast with music/jingles .. MP3 128 kbps stereo (or AAC 96k)
Music distribution .......... MP3 256–320 kbps / AAC 192–256 kbps
Master / archive ............ WAV or FLAC — always
One paragraph on sample rates: 44.1 kHz (CD heritage) and 48 kHz (video standard) are the only two you'll meet, and both capture the full range of human hearing. Pick 48 kHz if your audio will ever touch video, 44.1 kHz otherwise — and above all, keep one rate across your whole project to avoid pointless resampling steps.
A Clean Podcast Workflow in Four Steps
1. Record lossless. Capture in WAV at 48 kHz. Disk space is cheap; a take you compressed at the source is damaged forever. A browser-based Audio Recorder is enough for voice memos, remote inserts, or testing your mic chain before a session. If your source material is a video — an interview recorded on Zoom, a conference talk — Extract Audio pulls the audio track out so you can work on it directly.
2. Edit: cut, then assemble. Two operations cover 90% of podcast editing. First, trim: the dead air before you start talking, coughs, the tangent that went nowhere — an Audio Cutter handles precise trims with waveform view, no DAW needed. Then assemble: intro jingle + episode + outro, stitched in order with an Audio Merger. Keep your intro/outro as standing WAV files and reuse them every episode.
3. Export once, to MP3. When the edit is final, export a single distribution file: MP3, 96–128 kbps, mono for pure voice. Fill in the ID3 tags (title, show, episode art) — podcast apps display them.
4. Transcribe for show notes and SEO. Run the episode through Speech to Text and publish the transcript with the episode. Search engines can't listen to audio — a transcript is how a spoken answer becomes a page that ranks. It also gives you pull-quotes for social posts and makes your content accessible to deaf and hard-of-hearing listeners.
The One Rule: Never Re-Encode Lossy to Lossy
Each lossy encode throws data away — and a second encode discards different data from an already-damaged signal. MP3 → AAC → MP3 stacks artifacts the way photocopying a photocopy stacks blur: hiss, smeared transients, robotic voices. This is called generation loss, and it's the most common self-inflicted audio quality problem.
The rules that follow from it:
- Edit from your lossless original whenever it exists; export lossy exactly once, at the end.
- Converting lossy → lossless (MP3 → WAV) doesn't restore anything — it just makes the damaged file bigger. It's only useful as a working format before editing.
- If you must edit an MP3 you didn't record (no original available), do it in one pass: all cuts and merges, then a single re-export — not five successive save-as-MP3 rounds.
Convert Your First File
Whether you're shrinking a WAV master for upload or turning an M4A voice memo into a universal MP3, the Audio Converter handles every format in this guide — free, in your browser, files never leave your device, no account required.