Methodology

Understand what you measure.

BPM, key, loudness and peaks answer different questions. Find out how the tools calculate them and when to check the result by listening.

Headphones and audio interface — editorial listening study

A starting point for tempo

The BPM Index

The index contains editorial tempo references by genre, with production notes. Use it to choose a starting point; the analyzer estimates the tempo of a particular audio file.

Typical BPM
A reference value in the dataset. It is not a measured median of a documented sample of releases.
Tempo range
An editorial interval for exploring a genre, not a rule that every song must follow.
Half or double time
The same rhythm can be counted at two tempos. Check the pulse against the phrase and arrangement.

Dataset version: 2026-07-10-slashfix

Explore tempo ranges →

From your own audio

The audio analyzer

Your browser decodes and measures the file locally. The audio file is not uploaded to a server.

01 · LUFS / LRA

Read level and variation

Integrated LUFS describes overall loudness. LRA describes how much the measured loudness changes.

The implementation uses K-weighting, 400 ms blocks and absolute / relative gating. LRA uses loudness percentiles. These are local calculations; this page does not claim certified compliance.

02 · TRUE PEAK

Check peaks between samples

The dBTP result estimates peaks in the reconstructed signal, which can be higher than the stored samples.

The engine uses 4× oversampling with a windowed-sinc FIR interpolator. Lossy encoding can change the peaks: measure the encoded file again.

03 · BPM

Find a repeating pulse

A tempo estimate to check against the rhythm. Half-time and double-time readings can both fit the same music.

Spectral-flux autocorrelation searches from 50 to 200 BPM, with peak refinement and half / double-time heuristics.

04 · KEY

Check the tonal centre

An estimated major or minor key. Confirm the result with the melody and bass before choosing a harmonic transition.

A 12-bin chromagram is compared with major / minor profiles. The Camelot position is derived from the estimated key.

Read platform comparisons as estimates

The interface compares your measured LUFS with reference values configured in the tool. It does not simulate the full playback system or certify acceptance by a service. Use the comparison alongside peaks and listening, not as a compulsory mastering target.

Measure your file →

Keep listening

Where to check the result

  • Very short or silent files can trigger fallback values. They are not reliable material for judging tempo or dynamic range.
  • Rubato, changing tempo and polyrhythms can produce an ambiguous BPM estimate. Follow the phrase and check the pulse.
  • Modal music, modulation and microtonal material can confuse major / minor key detection.
  • Vocal / instrumental classification is a spectral estimate. It does not identify who is singing or separate the stems.
Understand LUFS with an example →

Technical references

ITU-R BS.1770 · EBU Tech 3342 · LRA

References explain the measurement methods. They do not certify this implementation. Reviewed 6 October 2026.