What Bitrate Means for Audio Quality
Bitrate is the number of bits per second used to represent the audio. Higher bitrate = more data = closer to the original WAV, but bigger files. Lower bitrate = smaller files, but the encoder has to discard more audio information.
A CD-quality WAV runs at 1,411 kbps (44,100 samples/sec × 16 bits × 2 channels). Converting to MP3 at 192 kbps means compressing that data to roughly 13.6% of the original size — and the encoder's job is to make that 13.6% sound as close to the original as possible.
CBR Bitrate Comparison: 128 vs 192 vs 256 vs 320
Here's how each Constant Bit Rate level compares for a typical 4-minute song:
| CBR Bitrate | File Size (4 min) | Compression Ratio | Quality | Best For |
|---|---|---|---|---|
| 128 kbps | 3.75 MB | 11:1 | Acceptable | Speech, podcasts, voice memos |
| 192 kbps | 5.6 MB | 7.3:1 | Good | General listening, streaming |
| 256 kbps | 7.5 MB | 5.5:1 | Very good | Music collections, critical listening |
| 320 kbps | 9.4 MB | 4.4:1 | Excellent | Archival, maximum MP3 quality |
The original WAV at CD quality takes ~40 MB for the same 4-minute song. Even at the highest MP3 bitrate (320 kbps), you save ~77% of the space.
VBR: Better Quality at Smaller Sizes
Variable Bit Rate encoding allocates bits dynamically — more for complex passages, fewer for silence and simple sections. This produces better quality at the same average file size compared to CBR.
| VBR Preset | Avg Bitrate | File Size (4 min) | Quality | Best For |
|---|---|---|---|---|
| V0 | ~245 kbps | ~7.2 MB | Transparent | Audiophile, archival |
| V2 | ~190 kbps | ~5.5 MB | Near-transparent | General music (recommended) |
| V4 | ~165 kbps | ~4.8 MB | Good | Podcasts, spoken word |
| V6 | ~130 kbps | ~3.8 MB | Acceptable | Voice recordings, low storage |
Recommendation: VBR V2 is the sweet spot for most people. It sounds indistinguishable from the original WAV for the vast majority of listeners and equipment, while producing files ~7x smaller. For a deeper comparison of VBR and CBR encoding methods, see our VBR vs CBR guide.
File Size Formula
For CBR MP3, the file size is predictable:
Quick reference for common durations:
| Duration | WAV | 128 kbps | 192 kbps | 320 kbps |
|---|---|---|---|---|
| 3 min | 30 MB | 2.8 MB | 4.2 MB | 7.0 MB |
| 5 min | 50 MB | 4.7 MB | 7.0 MB | 11.7 MB |
| 30 min | 302 MB | 28 MB | 42 MB | 70 MB |
| 1 hour | 605 MB | 56 MB | 84 MB | 141 MB |
How Convertio Encodes WAV to MP3
When you upload a WAV file, Convertio encodes it to MP3 using libmp3lame (LAME) — the gold-standard open-source encoder. By default, it uses VBR V2 (~190 kbps average). You can switch to CBR or adjust the quality/bitrate using the encoding options panel above.
Since WAV is uncompressed PCM audio, the encoder works with the full original signal — no generation loss from a previous lossy encoding step. This makes WAV-to-MP3 one of the cleanest possible conversion paths.
Tip: Need consistent volume across your converted files? You can also normalize loudness to a platform-specific LUFS target during conversion.