BPM Finder
Drop a song file into this BPM finder and it reads the tempo, marks every beat and plays a click track along with the music so you can hear that it fits.
Your file is analysed on this device and is never uploaded. MP3, WAV, M4A, OGG or FLAC, as your browser can read them.
Keyboard: Space play or pause, ↑ ↓ plus or minus 1 BPM, ← → 0.1 BPM, T tap along.
How to use the BPM finder
This BPM finder is a tempo finder for your own audio files: drop in a song and it reads the tempo to one decimal, marks every beat on the waveform and plays a click track with the music, all on your device, with nothing uploaded. Press Choose an audio file or drop a file on the box. The BPM finder decodes it, finds the beats and shows the tempo to one decimal, with the rounded BPM under it. A progress bar runs while it works; a three-minute song takes a few seconds. Your file is analysed on this device and is never uploaded.
Under the number you get a confidence line and three buttons: Half, Found and Double. The waveform shows the whole file with a thin line on every beat it found. Click the waveform to move the play position.
Press Play with clicks (or the Space bar) to hear the song with a click on every detected beat. If the clicks sit on the drums, the tempo is right. Clicks turns the click track on and off. If the clicks drift, use Adjust: plus or minus 1 BPM or 0.1 BPM (arrow keys Up and Down for 1, Left and Right for 0.1). Or press Tap (or the T key) on the beat four times or more while the song plays: your taps set the tempo and line the clicks up with your last tap. Reset goes back to the tempo that was found, and Send to metronome opens the metronome at the rounded BPM.
How the tempo is found
The BPM detector mixes the file to mono, lowers the sample rate to about 11 kHz and looks at the first three minutes. It cuts the sound into short slices about 6 milliseconds apart and measures how suddenly the energy rises in each frequency band. Drum hits and note starts make sharp peaks, and the result is a pulse curve of the song.
Next it compares the pulse curve with a shifted copy of itself for every tempo from 60 to 200 BPM. A song at 120 BPM lines up with itself every half second, and again at one, one and a half and two seconds, so each tempo is scored on eight of those repeats. Tempos near 120 get a small head start, because a pulse that fits 60 also fits 120 and a choice has to be made. The best tempo is then fine tuned to a tenth of a BPM, and a beat tracker places each beat, allowing a little drift, which gives the lines on the waveform and the click track.
Half time, double time and the confidence line
The same song can honestly be counted at two tempos. A hip hop track can feel like 85 or 170, and a ballad like 70 or 140. The finder picks one and offers the other two as buttons. Use the one that matches how the music is written or how you count it when you play.
The confidence line says how clearly one tempo stands out. High means the beat is strong and steady. Medium or Low means the pulse is weak or uneven, as with a solo piano, a string pad or a live band that speeds up. Check those by ear with the click track, or tap along on the tap tempo page.
When the BPM finder gets it wrong
No BPM analyzer can describe every song with a single number. Watch for these cases:
- Tempo changes. The tool gives one tempo for the first three minutes. After a tempo change the clicks drift away.
- Live recordings. Bands without a click track speed up and slow down a little. The beat lines follow that drift, but the number is an average.
- Swing and triplets. Music that divides the beat in three can be read as 4/3 of the real tempo, for example 120 for a song at 90.
- No clear beat. Ambient music, pads and free solos have little to lock on to, and the confidence drops.
In every case your ears win: play it with clicks, adjust, and tap if needed.
Note lengths at your tempo
Producers use the BPM to set delay and reverb times. One beat lasts 60,000 divided by the BPM in milliseconds. Here are the common note lengths for a few tempos (a quarter note is one beat):
| BPM | Quarter (ms) | Eighth (ms) | Dotted eighth (ms) | Sixteenth (ms) |
|---|---|---|---|---|
| 70 | 857 | 429 | 643 | 214 |
| 90 | 667 | 333 | 500 | 167 |
| 100 | 600 | 300 | 450 | 150 |
| 120 | 500 | 250 | 375 | 125 |
| 128 | 469 | 234 | 352 | 117 |
| 140 | 429 | 214 | 321 | 107 |
| 160 | 375 | 188 | 281 | 94 |
Want to play along? Program a groove at the same tempo on the online drums, or find the key of the same file with the song key finder.
More for timing: Metronome · Tap Tempo · Rhythm Trainer · Drums
Questions
Is my song uploaded anywhere?
No. The file is read and analysed by your browser on your own device. Nothing is sent to a server, and the file is gone when you close the page.
Which audio files work?
Any file your browser can decode, which usually means MP3, WAV, M4A (AAC), OGG and FLAC. If one does not open, convert it to MP3 or WAV and try again.
Can I find the BPM of a song by typing its name?
No. This song BPM finder has no song database. Use a file you have, or play the song and tap along on the tap tempo page.
How accurate is it?
On steady test tracks at 90, 120, 128 and 150 BPM it reads within 0.1 BPM, and the beat lines land on average within 5 milliseconds of the real beats. Real songs vary more: use the click track to check, and Half or Double if it picked the other count.
Why is the tempo half or double what I expected?
Both can fit the same beat. Press Half or Double to switch, and pick the one that matches how you count the song.
Why does it only analyse the first three minutes?
To keep it quick on phones. Most songs hold one tempo, and after three minutes the beat grid simply carries on at the same tempo.