How do I change the bitrate of an MP3?

This tool re-encodes an MP3 at a different bitrate — the single setting with the biggest effect on file size and quality. MP3 bitrates run from 32 to 320 kbps; the bitrate is literally how many kilobits describe each second of sound, so halving it halves the file. What it costs you depends on direction and content, as covered in the practical bitrate guide.

Lowering bitrate (320 → 128 kbps) shrinks files at a real but often acceptable quality cost — music keeps most of its character at 128 kbps, speech is untouched down to 64 kbps. Raising bitrate (128 → 320 kbps) is the trap to avoid: the encoder cannot invent detail the source never had, so the file gets bigger while sounding identical. The only good reason to re-encode upward is a device or platform that hard-requires a specific bitrate.

CBR (constant bitrate) versus VBR (variable bitrate) matters at the margins: CBR spends the same bits on silence as on a cymbal crash but is maximally compatible, notably with older car head units and hardware players; VBR spends bits where the music needs them and averages smaller at equal quality. When targeting old or picky hardware, choose CBR.

Reasons to convert MP3 to MP3 usually come down to compatibility, file-size, or specific feature requirements. Common situations:

• An app or platform only accepts MP3 uploads.
• You need a feature unique to MP3 (e.g. lossless editing, chapter markers, smaller streaming size, etc.) that MP3 doesn't provide.
• You're optimising file size — modern formats often produce smaller files than the older format you started with.
• You need a single archival format across a project so files behave consistently in the same viewer.

1. Open the MP3 → MP3 tool on mp3.now.
2. Drag your MP3 file onto the drop zone, or click Select files. You can drop a whole folder of files at once.
3. The output is fixed to MP3. If the format supports extra options (bitrate, sample rate, channels, volume normalization), tweak them in the options panel.
4. Click Convert. The job runs on our server and finishes in a few seconds for typical tracks.
5. Download the result. Files stay in storage for 24 hours and are then permanently deleted.

The entire flow is free for the first 10 jobs per day with no signup required. A free account doubles that quota; a premium plan removes the limit entirely.

• Down-converting saves space; up-converting only wastes it — quality never increases.
• One pass, not stages: go straight from source to target bitrate.
• Choose CBR for old car stereos and hardware players; VBR for everything modern.
• Speech survives 64 kbps easily; keep music at 128 kbps or above.
• Check the source's real bitrate first (shown in most players) so you know what you're working from.