Bitrate Checker
Check what bitrate an audio file really is, from both its codec header and its actual file size.
Convert with this tool
or choose a file from your device — it is processed in this tab and never uploaded
Accepted: MP3, WAV, FLAC, M4A/AAC, OGG, Opus
Files stay on your device. There is no upload, no queue and no watermark, so a conversion works even with the network switched off after the page has loaded.
Supported formats & processing
| Accepted input | MP3, WAV, FLAC, M4A/AAC, OGG, Opus |
|---|---|
| Produced output | An inspection report with a downloadable JSON file |
| Processing | Web Audio API + canvas + native JavaScript encoders |
| Upload required | No — the file is read locally and never transmitted |
How to use this tool
- Add the audio fileBoth figures are computed immediately.
- Compare the declared and measured bitratesA large gap means variable-bitrate encoding.
- Check whether the format is losslessFLAC and WAV have no quantisation loss, so re-encoding them is the only case where a higher rate helps.
- Look at the sample rateA low sample rate also caps the frequency content, independently of the bitrate.
- Decide whether to re-encodeThe bitrate converter can do it if the numbers justify it.
About this tool
The most common reason to check a bitrate is to decide whether re-encoding is worth doing. If a file is already 320 kbps, encoding it at 320 again achieves nothing but a generation of loss. If it is 96 kbps, the honest answer is that no amount of re-encoding will restore what was discarded.
This checker reports two figures that often disagree: the bitrate declared in the codec header, which for variable-bitrate files is a nominal average, and the measured bitrate, calculated from the real file size and the decoded duration. Where they differ significantly, the file is variable-bitrate and the measured figure is the one that reflects reality.
Features
- Declared bitrate read from the MPEG, FLAC or AAC header
- Measured bitrate calculated from the real file size
- Lossless status reported explicitly
- Sample rate and channel count alongside the bitrate
- Peak and RMS levels from the decoded audio
- Downloadable JSON report
Frequently asked questions
Does a higher bitrate mean better quality?
Only when the source has more information to preserve. Going from a 128 kbps source to 320 kbps cannot add detail that was already discarded. The bitrate sets the ceiling for an encode; the source sets the floor.
Why is the measured bitrate higher than declared?
Variable-bitrate files exceed their nominal average on complex passages. The declared figure is what the encoder targeted; the measured figure is what the file actually contains.
What bitrate should I aim for?
128 kbps for speech, 192 kbps as a general default, 256–320 kbps for music you care about. For lossless archiving, use FLAC or WAV and ignore the bitrate entirely.
Can I check a video's audio bitrate?
Yes — the video to MP3 tool will extract the audio and the resulting file's bitrate can be checked here. For the video stream itself, use the video info checker.