Metronome

How to use the metronome

1. Set the tempo in Tempo (BPM), with the slider, or with the Slower (−1), Faster (+1), −5 and +5 buttons. Any value from 20 to 300 beats per minute works.
2. Choose a Time signature. The circles show the beats of the bar; the first one is outlined.
3. Keep Accent the first beat ticked to hear a higher click on beat 1, or untick it for identical clicks.
4. Press Start. The click begins after your press, and the current beat lights up. Press Stop to end it.
5. Don’t know the tempo? Press Tap tempo in time with a song, at least three times. The tempo is set from the average of your last taps, and you can do it while the metronome is running.

The Volume slider only affects the click, not your system volume. The Tempo marking and Beat length below the controls tell you the Italian tempo name and the duration of one beat in milliseconds (60,000 ÷ BPM).

Why the timing stays steady

Browser timers such as setInterval can drift by tens of milliseconds when the page is busy, and they are slowed down in background tabs. This metronome doesn’t rely on them for timing. It uses a look-ahead scheduler: every 25 ms it checks which clicks fall in the next 100 ms and books each one at an exact time on the audio hardware clock. The audio engine then plays them sample-accurately, so the beat stays even when you scroll, switch apps or type. In a background tab it books clicks further ahead so they keep coming.

If you change the tempo while it plays, the next beat uses the new tempo, with no restart needed.

Time signatures and accents

The top number of a time signature is the number of beats in a bar; the bottom number is the note value that gets the beat.

• 2/4, 3/4, 4/4, 5/4: one click per quarter note. 3/4 is the waltz, 4/4 most pop and rock.
• 6/8, 9/8, 12/8: compound meters. This metronome clicks every eighth note and, with the accent on, adds a medium accent at the start of each group of three (beats 1 and 4 in 6/8). If you prefer to feel 6/8 “in two”, set the BPM to three times the dotted-quarter tempo.
• 7/8: grouped 2 + 2 + 3, the most common grouping in Balkan music and progressive rock.
• 1/4: every click is the same, a plain pulse.

In every signature the BPM counts the clicks you hear.

Practice tips

Start slower than you think: play a passage cleanly at a tempo where you make no mistakes, then raise it by 4–5 BPM at a time. Try placing the click on beats 2 and 4 only (set half the tempo and count the click as the backbeat) to build a solid groove. When a piece has a tempo marking, the table of Italian terms is a guide, not a rule: Adagio is roughly 66–76 BPM, Andante 76–108, Allegro 120–156, Presto 168–200, and sources disagree on the exact limits.