How WAVR finds the tempo
Every drum hit, pluck and chord stab makes the spectrum jump. WAVR measures that jump around 90 times a second, which gives a pulse that peaks wherever a new sound starts. It then asks at which spacing the pulse repeats best. At the right tempo the beat, two beats, a bar and two bars all line up, so each candidate is scored across 16 beats and the winner is refined to a hundredth of a BPM.
Tracks made to a click, which covers most house, techno, pop and hip-hop, give a steady pulse and the cleanest reading. Whole-number results are rounded to the nearest BPM, because that is almost always what the producer set.
Half time, double time and the BPM range
A drum & bass roller at 174 BPM and a half-time groove at 87 BPM can be the same audio counted two ways. Neither reading is wrong, so WAVR reports the tempo inside the range you choose:
- 85–175 (default): house, techno, trance, pop, most club music.
- 70–140: hip-hop, R&B, reggaeton, downtempo.
- 100–200: drum & bass, jungle, footwork, hardcore.
Typical tempos by genre
| Genre | Usual BPM |
|---|---|
| Hip-hop | 80–100 |
| Reggaeton | 88–100 |
| Amapiano | 110–115 |
| House | 120–128 |
| Techno | 125–140 |
| Trance | 132–140 |
| Dubstep | 140 (felt as 70) |
| Drum & bass | 170–176 |
Where detection struggles
Live drummers drift, so you get the average tempo. A DJ mix or a track that changes tempo also gets one average; very long files are measured on their middle 12 minutes. Ambient and beatless music has no pulse to lock onto, and WAVR says so instead of guessing. Each result shows a confidence figure so you know which ones to check by ear.
Write BPM and key into your files
Results go into the standard tags: TBPM and TKEY in MP3, WAV and AIFF, BPM and INITIALKEY in FLAC and OGG, and tmpo plus initialkey in M4A. Convert the files, or use Download originals with new tags to keep the audio exactly as it was. Tracks that already have BPM and key tags keep them unless you untick Keep existing BPM/key tags.
BPM finder questions
Why does a track show half or double its tempo?
A beat at 87 BPM and one at 174 BPM land on the same drum hits, so both are valid readings. Pick the BPM range that matches how you count the genre and detect again.
Will the result match Rekordbox or Mixed In Key?
On music made to a click it usually agrees, apart from half or double readings. Analyzers use different methods, so a few tenths of a BPM or a different octave on live or swung music is normal. Trust your ears on the low-confidence ones.
Which DJ apps read the BPM tag?
Rekordbox, Serato, Traktor, VirtualDJ, Engine DJ and Apple Music read the standard BPM tag WAVR writes. Some apps re-analyze on import anyway; check the setting that controls whether they trust file tags.
Is my music uploaded?
No. Analysis runs in a background thread in your browser. Unreleased promos and edits stay on your device.
Is BPM detection free?
BPM and key detection is a Pro tool, open to everyone while Pro is in beta. Converting is always free. See pricing.