Why WAV files are so big
WAV stores audio uncompressed: every sample, of every channel, many thousands of times a second. CD-quality stereo (16-bit, 44.1 kHz) runs at 1,411 kbps, about 10 MB per minute, so a one-hour recording is over 600 MB. Studio and field recorders often use 24-bit or 48 kHz, which is bigger still.
That's ideal while you're recording and editing, but awkward for everything after: emailing a demo, uploading a podcast, putting music on a phone or sending a voice recording over a messaging app.
What quality is the MP3?
The MP3 is encoded with LAME at a constant 192 kbps, about 1.4 MB per minute, roughly seven times smaller than CD-quality WAV. For speech it's indistinguishable from the original, and for most music it's very hard to tell apart in normal listening.
It's a good default for sharing finished work. Keep the WAV as your master if you might edit, remix or master the audio again later: MP3 is the delivery format, not the working one.
Where do WAV recordings come from?
Common sources that hand you WAV files:
- Portable recorders (Zoom, Tascam, Sony) and lavalier and USB mics that record straight to WAV.
- Audio editors such as Audacity, GarageBand, Logic, Reaper and Adobe Audition, which export WAV by default.
- Windows Voice Recorder on some versions, call recorders and dictation devices.
- Sample packs, sound effects libraries and DAW bounces.
What bitrate should a podcast MP3 be?
Most podcast hosts recommend MP3 at 128–192 kbps for speech. Converting before uploading saves time on slow connections and avoids the host's own conversion, which may be at a lower quality. For music demos sent to friends, bands or labels, an MP3 opens instantly on any phone, while a large WAV often can't be previewed in email or chat apps at all.
The conversion runs in your browser, so unreleased tracks and private recordings never leave your device, and there's no upload to wait for, which matters with WAV's file sizes.
High-resolution and mono recordings
Studio and field recorders often save 24-bit WAV at 48 kHz or higher. Those convert normally. MP3 itself tops out at a 48 kHz sample rate, so recordings at 88.2 or 96 kHz are resampled to 48 kHz on the way. That change is far above the range of human hearing, so you won't notice it in the MP3.
Mono recordings, typical of voice memos, interviews and lavalier mics, stay mono. At 192 kbps a mono MP3 is generous for speech, so voice recordings sound exactly like the original.
Keep the WAV as your master
MP3 is a delivery format. If there's any chance you'll edit the recording again, such as trimming, mixing or remastering, keep the original WAV and convert a fresh MP3 from it each time. Editing an MP3 and saving it as MP3 again stacks compression on compression, and the losses add up with every round.