Bitrate is the single setting that decides how good a compressed audio file sounds and how big it is. Pick too low and music sounds flat; pick too high and you waste space on quality no one can hear. Here's what the numbers mean and how to choose the right one.
Bitrate is the amount of data used to store each second of audio, measured in kilobits per second (kbps). A 320 kbps MP3 uses 320 kilobits to describe every second of sound; a 128 kbps MP3 uses less than half that. More data per second means the format can preserve more detail — so within the same format, higher bitrate means higher quality and a proportionally larger file.
| Bitrate | Quality | Roughly per minute | Best for |
|---|---|---|---|
| 128 kbps | Acceptable | ~1 MB | Speech, podcasts, voice notes, audiobooks |
| 192 kbps | Very good | ~1.4 MB | Music for everyday listening — the sweet spot |
| 320 kbps | Excellent (max for MP3) | ~2.4 MB | Music you care about, or files you'll edit further |
Voice doesn't need much data to sound clear. A podcast, interview, lecture or voice memo at 128 kbps sounds clean and keeps files small, which matters when you're hosting episodes or emailing recordings. Going higher for pure speech mostly just adds megabytes with little audible benefit.
For most people, on most equipment, 192 kbps MP3 is genuinely hard to tell apart from the original. It's the best balance of quality and size for songs you'll listen to on phones, in cars, or through everyday earbuds and speakers.
320 kbps is the highest standard MP3 bitrate. It's the choice when you want the best MP3 can offer — for good headphones, a nice stereo, or a track you'll keep. It's also the safer pick if you plan to edit the file again later, since you start from more detail.
The numbers above are constant bitrate (CBR), where every second uses the same data. Variable bitrate (VBR) is smarter: it spends more data on complex passages and less on simple ones, often giving similar quality at a smaller average size. VBR is great for music libraries; CBR is more predictable and widely compatible, which is why fixed values like 128/192/320 remain the common presets.
It contains more detail, yes — but whether you can hear the difference depends on the audio and your equipment. For speech, rarely. For music on good headphones, sometimes. For casual listening, usually not.
Yes, roughly proportionally. 320 kbps files are about 2.5× the size of 128 kbps files of the same length.
A CD is uncompressed (equivalent to well over 1,000 kbps). No MP3 bitrate literally matches it, but 320 kbps gets close enough that most listeners can't distinguish them in normal conditions.
In the AudioTrim editor, the Download section lets you export MP3 at 128, 192 or 320 kbps — just pick the one that matches your use case above.
Related: MP3 vs WAV vs FLAC vs M4A · How to reduce audio file size · All guides