10 May 2026 | 6 min read
MP3 bitrate explained: what 128, 192 and 320 kbps actually change
Bitrate is a budget. The encoder spends it on the parts of the sound it thinks you will notice, and runs out earlier than you would like at low settings.
Bitrate is how many bits per second the encoder is allowed to spend describing your audio. At 320 kbps it has plenty of budget. At 128 kbps it has to make hard choices, and those choices are the artefacts you hear on cymbals, sibilance and reverb tails.
Size and quality at a glance
- 128 kbps: about 1 MB per minute. Fine for speech, audible on music.
- 192 kbps: about 1.4 MB per minute. A reasonable everyday compromise.
- 256 kbps: about 1.9 MB per minute. Transparent for most listeners.
- 320 kbps: about 2.4 MB per minute. The MP3 ceiling, use it when quality matters more than size.
Constant, variable and average bitrate
Constant bitrate spends the same budget every second, even on silence. Variable bitrate adapts, spending more on complex passages and less on simple ones, usually giving better quality per megabyte. Average bitrate splits the difference and is predictable in size. For delivery to unknown players, constant is the safest bet.
Where bitrate is not the problem
A muddy MP3 made from a clean master is a bitrate problem. A muddy MP3 made from a lossy source is a generation problem, and no bitrate fixes it. Always encode from the original WAV, never from an earlier MP3.
Practical choices
- Client review of a mix: 320 kbps constant, stereo.
- Podcast episode, spoken word: 128 to 192 kbps, mono if the distribution is mono.
- Reference on a phone during a shoot: 192 kbps is plenty.
- Anything that will be edited again: not MP3 at all, use WAV.
The exporter here writes MP3 at 320 kbps and downmixes multichannel material to stereo automatically, so a poly WAV becomes a listenable reference in one step, entirely in your browser.