How to use it
- Press Tap in time with the beat, or press the space bar. Two taps are enough for a first reading.
- Keep tapping; the Tempo is the median of your last gaps, so one late tap hardly moves it.
- To read a file, choose it under Tempo of an audio file and wait for Tempo of the file.
- Press Reset taps to start again.
Tapping the tempo
Each tap is timed. The tempo is 60 000 divided by the median of the gaps between taps, in milliseconds, so one early or late tap moves it very little. A pause of more than two seconds starts a new count, and the last eight gaps are used.
BPM = 60 000 ÷ median gap (ms)Steadiness
Steadiness is the spread of your gaps as a percentage of their mean. Under 3 % is steady, 3 to 8 % is fair, and more is unsteady, which usually means the beat is drifting. The steadiness does not change the tempo; it tells you how far to trust it.
The tempo names
The names come from the ranges in Wikipedia's Tempo article, which list Largo at 40 to 66 BPM, Andante at 56 to 108, Moderato at 108 to 120, Allegro at 120 to 156, Vivace at 156 to 176, and Presto at 168 to 200. Those ranges overlap, so the page gives each tempo one band:
| Name | BPM |
|---|---|
| Larghissimo | 24 and under |
| Largo | 25 to 66 |
| Andante | 67 to 108 |
| Moderato | 109 to 119 |
| Allegro | 120 to 156 |
| Vivace | 157 to 176 |
| Presto | 177 to 200 |
| Prestissimo | 201 and over |
Tempo from an audio file
The file is decoded in your browser, and its first two minutes are analysed. The page measures the loudness of every 10 milliseconds, finds the rises in loudness, and looks for the spacing that repeats most strongly between 50 and 200 BPM. It prefers 120 BPM over its double and half, which is the usual choice for music. A recording with no steady beat, such as speech, gives a low clarity.
Example: taps 500 ms apart
Taps 500 ms apart give 60 000 ÷ 500 = 120 BPM, which the tempo names put in Allegro. If one tap comes 800 ms after the last, the median of the gaps is still 500 ms, so the tempo stays at 120 BPM.
Frequently asked questions
How many taps do I need?
Two taps give a first reading, since one gap is enough. More taps give a steadier figure, and the page uses the last eight gaps of the current run.
Can I tap with the space bar?
Yes. While the page or the tap button has the focus, the space bar counts a tap, so you can keep time without the mouse. Fields you type in are not affected.
Why does the file give a different tempo from my taps?
Tapping follows your sense of the beat, while the file method looks at the loudness pattern. Swing, strong off-beats or a changing tempo can give a different figure, so compare the clarity with the steadiness of your taps.
What does the clarity figure mean?
It measures how strongly the beat repeats at the chosen tempo. A figure near 1 is a clear, steady beat; a low figure means the page found no clear beat, as with speech or noise.
Is my audio file uploaded?
No. The file is decoded in your browser and analysed in a background worker on your device. Nothing is sent or stored, and only the first two minutes are used.
Sources
- Tempo, Wikipedia (tempo markings and their ranges)
- Web Audio API, W3C specification (decoding audio data)
Figures and text last checked on Tuesday, November 10, 2026.