Metronome
A precise classroom metronome with tap-tempo, a swinging pendulum, and an accented downbeat for any time signature. Set BPM by hand or tap out the rhythm yourself.
Built by the AbraCalc team
How to play
- Set the tempo with the slider, the +1 / −1 buttons, or by tapping Tap Tempo in rhythm a few times.
- Choose a time signature (2, 3, 4, or 6 beats per bar) to match the accent pattern you need.
- Tap Start to hear the click and watch the pendulum swing and the beat dots light up, with the downbeat in amber.
- Tap Stop to pause, adjust the tempo or signature, and Start again — the beat always restarts clean from beat one.
Set a tempo from 30 to 240 BPM with the slider or the plus and minus buttons, or simply tap the Tap Tempo button in rhythm a few times and the exact BPM is calculated from the spacing between your taps. A swinging pendulum and a row of beat dots track the tempo visually, with the downbeat of each bar marked in amber and lit up as it lands, so a room full of students can follow along even with the sound off. Choose a time signature of 2, 3, 4, or 6 beats per bar to match whatever piece or rhythm exercise the class is working on. The click itself uses precise look-ahead audio scheduling rather than a simple timer, so the beat stays accurate and doesn't drift even if the tab is busy doing other things. Built for music class rhythm work, but useful anywhere a steady, visible pulse is needed.
How it works
The Online Metronome keeps precise musical time by producing an audible click at a set tempo measured in beats per minute (BPM). Set the desired BPM using the input or slider, choose the number of beats per bar, adjust the click volume, and press Start. The metronome uses the Web Audio API's internal clock for accurate timing that is not affected by JavaScript event loop delays.
The first beat of each bar is accented with a higher-pitched click so you can hear the downbeat clearly. This is helpful when practicing rhythmic patterns, counting measures, or coordinating multiple instruments or voices.
Use the metronome for practicing an instrument at a controlled tempo, gradually increasing speed to build technique, maintaining steady rhythm during recording, or keeping time during a performance rehearsal. Common reference tempos: 60 BPM is slow (one beat per second), 120 BPM is moderate, 180 BPM is fast.
Worked example
Practice a passage at a slow tempo and gradually speed up
- Set BPM to 60 and beats per bar to 4.
- Click Start and play through the passage, keeping exactly with the click.
- When the passage feels comfortable, increase BPM by 5.
- Repeat until you reach your target performance tempo.
Improved technical accuracy and muscle memory developed at progressively faster tempos.
Common mistakes to avoid
- Starting at the target tempo immediately instead of learning the piece slowly and building up -- slow practice prevents ingrained mistakes.
- Tapping along loosely instead of playing precisely on each click, which defeats the purpose of using a metronome.
- Switching the browser tab to the background during practice, causing timing drift in the click track.
Key terms
- BPM (beats per minute)
- A measure of musical tempo; 60 BPM means one beat every second, 120 BPM means two beats per second.
- Time signature
- A notation indicating how many beats are in each bar, e.g. 4/4 has four beats per bar, 3/4 has three.
- Downbeat
- The first and typically accented beat of a bar.
Frequently asked questions
- How accurate is the timing compared to a simple JavaScript timer?
- The metronome uses WebAudio's own clock with look-ahead scheduling, queuing each click slightly before it plays, which avoids the drift you get from a plain setInterval-based timer over long sessions.
- How does Tap Tempo work?
- Tap the button in rhythm at least twice; the tool measures the time between your taps, averages the intervals, and converts that average directly into a BPM value between 30 and 240.
- Can I use it for compound or irregular time signatures?
- You can choose 2, 3, 4, or 6 beats per bar, which covers the most common classroom rhythm exercises; the first beat of each bar is always the accented downbeat.