How it works.
A clear explanation for every number and every click.
Start with a clear beat reference
Metronome BPM counts click pulses per minute. Tap tempo counts your taps per minute. The note-duration calculator always uses a quarter-note BPM reference. A compound-meter main beat and its subdivisions are different pulses; choose which one you want to count.
How the metronome schedules a click
The interval is 60 ÷ BPM seconds. A scheduler checks every 25 milliseconds and sends short tones to the Web Audio clock about 120 milliseconds ahead. The first beat is 1320 Hz and the remaining beats are 880 Hz, with a short attack and decay. System load and output-device latency can still affect playback.
How tap tempo handles uneven taps
The rolling window keeps up to 13 taps. A gap above 3 seconds restarts it; a tap less than 150 milliseconds after the last is ignored. Intervals must be 200–3,000 milliseconds. Intervals within 25% of their median are averaged for BPM. Consistency is based on their coefficient of variation; a small sample needs more taps.
Calculating notes and bars
Regular note milliseconds = (60,000 ÷ BPM) × (4 ÷ note denominator). Multiply by 1.5 for a dotted note or 2/3 for a triplet. A bar lasts (60,000 ÷ BPM) × numerator × (4 ÷ denominator). For example, a 4/4 bar at 120 BPM lasts 2,000 milliseconds.
Practice rounds and real elapsed time
Total time is practice duration × rounds + rest duration × (rounds − 1). There is no rest after the last round. The timer reads actual elapsed time from performance.now(); screen updates do not increment its clock. Pause stores elapsed time and Resume starts from that point.
Background and audio limits
Audio starts only after pressing Start. Hiding the page stops the metronome and pauses the practice timer; returning does not resume them. Switching tools clears the previous tool’s audio and timing tasks. The site does not provide lock-screen playback, background alarms or professional measurement guarantees.