How to use the metronome
- Set the tempo in beats per minute (BPM): type it, drag the slider, or use − and + for one BPM at a time. The range is 20 to 300 BPM.
- Choose beats per bar — 4 for most pop and rock (4/4), 3 for a waltz (3/4), 2 for a march, 6 to count 6/8 in six. The first beat of each bar gets a higher, louder click while Accent the first beat is on, and the dots show where you are in the bar.
- Choose clicks per beat to hear subdivisions: eighth notes (2), triplets (3) or sixteenth notes (4). The extra clicks are softer and lower than the beat.
- Press Start (or the Space bar). You can change the tempo while it plays; it switches on the next click.
Tap tempo: to find the speed of a song, press Tap tempo in time with the beat, at least three or four times. The metronome averages the gaps between your last taps (up to eight) and sets that tempo; pause for more than two seconds to start a new measurement.
Why the timing stays steady
A metronome built on ordinary JavaScript timers drifts and stutters, because the browser runs those timers late whenever it is busy. This one uses the approach known as “a tale of two clocks”: a light timer wakes up every 25 milliseconds and books the next clicks about a tenth of a second ahead on the audio hardware’s own clock (the Web Audio API). The sound card then plays each click at exactly its booked sample, so a late timer never makes a click late. When the tab is in the background, browsers wake timers only about once a second, so the metronome books 1.5 seconds ahead instead and keeps going. The flashing dots follow the same audio clock, so they light up with the sound you hear. Everything runs in your browser; nothing is downloaded or sent anywhere.
The arithmetic is simple: one beat = 60,000 ÷ BPM milliseconds, and a bar lasts beats per bar × one beat. At 120 BPM a beat is 500 ms, a 4/4 bar is 2 seconds, and 30 bars fit in a minute.
| BPM | Beat (ms) | Eighth note (ms) | Triplet (ms) | Sixteenth (ms) |
|---|---|---|---|---|
| 60 | 1,000 | 500 | 333.3 | 250 |
| 80 | 750 | 375 | 250 | 187.5 |
| 100 | 600 | 300 | 200 | 150 |
| 120 | 500 | 250 | 166.7 | 125 |
| 140 | 428.6 | 214.3 | 142.9 | 107.1 |
| 160 | 375 | 187.5 | 125 | 93.8 |
| 180 | 333.3 | 166.7 | 111.1 | 83.3 |
Tempo markings and their BPM
Classical scores describe speed with Italian words. The ranges below are the ones this page uses for the Tempo marking card; treat them as rough guides, because sources disagree widely. Wikipedia’s “Tempo” article, for instance, lists Andante as about 56–108 BPM, while the LibreTexts textbook Music Appreciation II gives 73–77, and composers used the words for character as much as for speed.
| Marking | Meaning | About (BPM) |
|---|---|---|
| Grave | very slow, solemn | 20–39 |
| Largo | broad, slow | 40–59 |
| Larghetto | rather broad | 60–65 |
| Adagio | slow, at ease | 66–75 |
| Andante | at a walking pace | 76–107 |
| Moderato | moderate | 108–119 |
| Allegro | fast, bright | 120–155 |
| Vivace | lively, fast | 156–167 |
| Presto | very fast | 168–199 |
| Prestissimo | as fast as possible | 200+ |
The pendulum metronome was patented by Johann Nepomuk Maelzel in 1815 (the mechanism itself was invented a year earlier by Dietrich Nikolaus Winkel in Amsterdam), and Beethoven was one of the first composers to use it: in 1817 he published metronome marks for his eight symphonies.
Practicing with a metronome
- Start slow. Find the tempo at which you can play a passage cleanly three times in a row, then raise it by 2–5 BPM. Going back down a step when it falls apart is part of the method.
- Use subdivisions for fast runs and syncopation: eighths or sixteenths show whether the notes between the beats are even.
- Feel beats 2 and 4. For swing and backbeat grooves, turn the accent off and halve the tempo, so each click lands where the snare drum would.
- Count in. Let one full bar play before you start, so the accented click marks your first note.
- Time the session with the timer, and tune first with the guitar tuner — practicing in tune trains your ear too.
Frequently asked questions
What BPM is a song?
Press Tap tempo along with the beat for a few bars; the metronome shows the average tempo of your taps. If the number seems twice or half what you expected, you were tapping every other beat or every half beat.
Does it keep running in a background tab or with the screen off?
In a background tab, yes: the clicks are booked ahead on the audio clock, so they stay on time even when the browser slows the page down. With the screen off, a phone may pause the page; keep the screen on while you practice.
How do I set 6/8 or 12/8?
Count it either way: 6 beats per bar at the eighth-note pulse, or 2 beats per bar (4 for 12/8) with Triplets as clicks per beat, which puts the main beat on the dotted quarter note and the three eighths between.
Why is there no sound on my iPhone?
Check the volume and the ringer switch. The metronome asks Safari to treat it as media playback, which plays even in silent mode on versions that support this; on others, web audio stays muted while the switch is on silent.
Is the beat light delayed with Bluetooth headphones?
Bluetooth adds a delay between the audio and your ears. The dots follow the audio clock and the output delay the browser reports, so they stay in step when the headphones report their delay; when in doubt, play along with the sound, not the light.
Last updated: October 15, 2026