Audio Analyzer
LUFS, True Peak, BPM, Key, Stereo Width, Frequency Spectrum — everything runs locally in your browser. No uploads.
100% local processing — your audio never leaves your device.
Decoding audio…
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Click or drag the waveform. Arrow keys fine-tune the playhead, even while paused.
Spectrum
Channel power average · 8,192-point Hann FFT · Same scale in every view
Goniometer
Vertical: mono · Horizontal: opposing phase
Correlation
History: 400 ms windows · The vertical marker follows the playhead
At playhead
- Sample peak dBFS
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- RMS dBFS
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- Crest factor dB
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- Side-energy width %
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Streaming Platform Targets
Comparison presets, not mandatory mastering levels. Actual playback depends on each service’s settings and track/album normalization. Spotify’s guidance ↗
How to read these measurements
Whole file averages the entire decoded signal. At playhead uses the selected window centred around the cursor, shifted inward at the ends. Compare both overlays the two spectra and stereo plots; the live metrics show the position window alongside the file reference.
Spectrum combines channel power so opposite-polarity left and right channels do not disappear. Silence and a missing channel produce no correlation value. Negative correlation can indicate cancellation when summed to mono; it is not a universal quality score.
Loudness uses BS.1770 K-weighting and absolute/relative gating for mono and stereo. Multichannel loudness needs a known channel layout and is not reported here. True peak is an oversampled estimate, not a certified compliance result. Short clips may not contain enough audio for integrated loudness or loudness range.
Playback volume changes listening level only. Measurements refer to the decoded buffer, which may be resampled by the browser. Tempo and key are estimates from up to 90 seconds and can be unreliable for speech, ambience or unpitched material.
100% local processing — your audio never leaves your device