How this calculator works
Tempo in beats per minute counts musical beats, and the time signature says which note value gets one beat. In 4/4 a beat is a quarter note, so 120 BPM means 120 quarter notes per minute, or one every half second. In 6/8 a beat is usually an eighth note, so the same 120 BPM gives a beat every quarter second and a bar of six eighths every 1.5 seconds. Bars per minute follow from the bar length: 120 BPM in 4/4 is 60 bars per minute, while 120 BPM in 6/8 is 40 bars per minute. The note value table converts the tempo to whole, half, quarter, eighth and sixteenth note lengths, including dotted and triplet forms.
Formula
quarter note length (s) = 60 / BPM. beat length = quarter note length x 4 / time signature denominator. bar length = beats per bar x beat length. BPM = 60 x (4 / denominator) / beat length.
Worked example
At 120 BPM in 4/4, a quarter note lasts 60 / 120 = 0.5 seconds, a beat also lasts 0.5 seconds, and a four-beat bar lasts 2 seconds. At 90 BPM in 3/4, a quarter note lasts 0.667 seconds and a bar lasts 2 seconds. At 120 BPM in 6/8, one beat is an eighth note of 0.25 seconds and a bar of six eighths lasts 1.5 seconds.
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Frequently asked questions
Does BPM always mean quarter notes?
In 4/4 and most simple time signatures, yes. In compound time such as 6/8 the beat is the dotted quarter in practice, while the time signature names the eighth as the unit. This page uses the denominator as the beat unit, which matches the notation and most tempo markings.
How do I count BPM without a metronome?
Tap a steady pulse on a table or phone for several beats while watching a clock, then divide 60 by the seconds between taps. Tapping for 15 seconds and counting the taps gives an estimate: 30 taps in 15 seconds is 120 BPM. Averaging over more taps smooths small timing errors.
What is the difference between tempo and BPM?
Tempo is the musical sense of speed, and BPM is its numeric measure. A tempo marking such as allegro covers a range, while BPM pins the speed. Producers work in BPM because the grid of a digital audio workstation is set in beats, and delays and loops lock to that grid.
Why do dotted and triplet values matter?
Dotted notes last one and a half times the plain value, and triplets last two thirds. A dotted eighth delay is a common rhythmic echo, and triplet delays fit shuffle and swing feels. The table gives the exact milliseconds so you can type them into a delay plug-in.