Beat and tempo

At 60 beats per minute a beat lasts exactly one second; at 120 it lasts half a second, and the music feels twice as fast.

The pulse you tap your foot to

Put on almost any song and within a few seconds your foot or head starts moving at a steady rate. That steady, repeating pulse is the beat. It is not always a sound you can point to: sometimes a drum plays exactly on it, sometimes a singer holds a long note across several beats and you still feel the beats go by underneath. Rhythm, the pattern of long and short sounds in a piece, is heard against this grid of beats. A rhythm only makes sense because you know where the beats are, the same way the length of a word only makes sense if you know how fast someone is talking.

Music theory books describe the beat as one layer among several pulses running at once. Faster pulses split each beat into smaller pieces, and slower pulses group beats into bars. The beat is the layer you would naturally count or tap, which is why it is also called the counting pulse. This course starts with that layer and builds the faster and slower ones around it in later units.

Tempo in beats per minute

Tempo is how fast the beats go, and the usual unit is beats per minute, written BPM or bpm. The arithmetic is short: one beat lasts 60 ÷ BPM seconds. At 60 BPM that is 1 second, at 80 BPM 0.75 seconds, at 96 BPM 0.625 seconds and at 120 BPM 0.5 seconds. A bar of four beats at 120 BPM lasts 2 seconds. Doubling the tempo halves every duration; nothing else about the rhythm changes. That is why a band can play the same written song slower for a ballad version without rewriting a single note.

Before numbers, composers described tempo with Italian words, and you still see them at the top of printed music. Largo means broad, adagio roughly at ease, andante walking, moderato moderate, allegro cheerful and presto quick. These words tell a player the character as well as the speed, but they leave the exact number open, so two performers can read "allegro" quite differently. A metronome mark, such as ♩ = 96, removes that doubt: it names the note that counts as the beat and how many of them fit in a minute.

Keeping a steady beat

Playing in time is a skill you practise, and the metronome is the usual tool. Two habits help most. First, count out loud, "1, 2, 3, 4", because saying the numbers keeps your place even when the notes are long. Second, practise below the target tempo: if a passage is meant to go at 120, play it cleanly at 80 and raise the number a few beats at a time. Very slow tempos are hard in their own way, since the long gaps make it easy to rush. The rhythm lab below can play any tempo from 40 to 200 and can also measure one: tap the Tap tempo button along with a song and it divides 60 by the average gap between your taps.

In the Tap along tab, press Start, listen to one bar of clicks, then tap on every note. The panel shows how many taps landed, the average error and whether you tend to tap early or late. A tap within 50 milliseconds of the target is shown green. At 80 BPM a beat is 750 milliseconds, so 50 milliseconds is exactly a fifteenth of a beat. Expect the first tries to be early: most people rush when they concentrate.