Best Audio Format for Voice Recordings

What your device records by default

Most devices don't give you a choice. They record in whatever format they're built around:

• →iPhone Voice Memos: M4A (AAC in MPEG-4 container). Good quality, compact, works in the Apple ecosystem. Convert to MP3 if you need it on other devices or platforms.
• →Android voice recorders: Varies by app. Common defaults are AMR (low quality), AAC, or MP3. If the app allows format selection, choose AAC or MP3 at the highest available bitrate.
• →Dedicated voice recorders (Olympus, Zoom, Tascam): Usually offer MP3 or WAV. If you plan to edit or archive the recording, select WAV. If you just want a small file to share or transcribe, MP3 at 192 kbps is fine.
• →Zoom calls, Google Meet, Teams recordings: Often MP4 video with AAC audio, or MP3 depending on the client. If you want audio-only, extract the audio track.

For sharing: MP3

If you're sending a voice recording to someone — by email, messaging app, or shared folder — MP3 at 128 kbps is the right format. Voice recordings compress well at this bitrate (speech doesn't have the complex high-frequency content that music does), and the resulting file is small enough to share without any friction.

A one-hour voice recording at 128 kbps is about 57 MB. The same recording as M4A (AAC at similar bitrate) would be comparable in size, but MP3 is more universally compatible — the recipient doesn't need to be on an Apple device or have specific software.

If you have an iPhone Voice Memo (M4A) and need to share it broadly, converting M4A to MP3 is a one-step process. The quality difference at 128 kbps output is inaudible for speech.

For transcription: format barely matters

Transcription services — Otter.ai, Descript, Rev, Whisper, and similar — process audio by converting it to their own internal format before analysis. They accept MP3, M4A, WAV, FLAC, and often MP4. The format you submit in doesn't meaningfully affect transcription accuracy.

What does affect accuracy is audio quality: background noise, multiple overlapping speakers, low recording volume, and heavy compression. A clean, quiet recording transcribes well regardless of format. A noisy recording transcribes poorly regardless of format.

Submit whatever format you already have. Don't convert just for transcription.

For editing: convert to WAV first

If you need to edit a voice recording — cut sections, remove filler, adjust levels, add music — convert it to WAV before you start. The reason is that MP3 and M4A are lossy formats, and editing software that saves back to a lossy format will re-encode the file each time you save. Each re-encode adds another round of compression degradation.

Converting to WAV first sets a quality ceiling and holds it there. You can edit and save the WAV as many times as needed without additional quality loss. When you're done, export once to your final format — MP3, M4A, whatever fits the destination.

This is especially important for longer recordings like interviews or meeting recordings, where you might open and re-edit the file multiple times over several sessions.

For archiving important recordings: FLAC

If a recording matters — an interview you might quote from, a live performance, a legal record, an important meeting — archive it in a lossless format. FLAC is the practical choice: the same audio quality as WAV at 40–60% smaller file size.

The logic is forward-looking. You don't know what you'll want to do with a recording in three years. If you've archived as MP3 and later need to re-process it, re-edit it, or improve the audio with new tools, you're starting from a degraded source. Starting from FLAC gives you full headroom.

For recordings that aren't particularly important — a quick note to yourself, a voice memo you'll delete after listening once — MP3 is perfectly fine. The archiving logic applies when the recording has long-term value.

Decision by use case