BPM to Milliseconds & Note Duration Calculator

A live calculator for turning tempo into time, with a guide to the math and how to use it.

Turn a tempo into time

This page pairs a live calculator with a plain-English guide to converting tempo into time. Enter a tempo in beats per minute (see our guide to what BPM is) and the tool returns the length of one beat in milliseconds, plus the duration of every common note value: whole, half, quarter, eighth, and sixteenth, including their dotted and triplet variants, shown in both milliseconds and hertz. A reverse field turns a measured delay time back into a tempo. The short answer, if that is all you need: BPM means beats per minute, and one beat lasts 60000 divided by the BPM in milliseconds. At 120 BPM that is 60000 / 120 = 500 ms per beat. Everything else on this page builds on that single relationship.

How to use the calculator

Type your tempo into the BPM field at the top of the calculator. The panel immediately shows one beat in milliseconds and, below it, a table of note durations: whole, half, quarter, eighth, and sixteenth notes, each with a dotted (times 1.5) and triplet (times 2/3) column. Every cell lists the value in milliseconds and its matching frequency in hertz, so you can copy a number straight into a delay plug-in or an LFO rate. If you already have a time and want the tempo, use the reverse field: enter a delay time in milliseconds and the calculator returns the BPM it corresponds to. Values update as you type. If you do not know your tempo yet, our tap tempo tool can find it.

The math behind it

In 4/4 the quarter note receives one beat, so the quarter-note length equals the beat length: 60000 / BPM milliseconds. From there the note values scale by simple factors, because each note value is a subdivision of the beat. Each shorter value halves the previous one (an eighth is half a quarter, a sixteenth half an eighth), and each longer value doubles it (a half note is two quarters, a whole note is four). A dot adds half the note's value, so a dotted note is the plain value times 1.5. A triplet fits three notes in the space of two, so each triplet note is the plain value times 2/3. Frequency is the reciprocal: a duration of t milliseconds repeats at 1000 / t hertz, which is why the beat rate at 120 BPM (500 ms) is exactly 2 Hz. This is the everyday math behind tuning time-based effects. To sync a delay to a dotted-eighth pattern at 120 BPM you take the eighth (250 ms) times 1.5 = 375 ms; set the same figure as an LFO period and the modulation locks to the groove.

Worked examples

A few concrete cases make the pattern clear. At 120 BPM the beat is 60000 / 120 = 500 ms, so an eighth note lasts 250 ms, a sixteenth 125 ms, and a whole note 2000 ms. At 90 BPM the beat is 60000 / 90 = 666.7 ms; the eighth note is 333.3 ms and a dotted eighth is 500 ms, a round figure that is easy to dial in by ear. For a delay example, the classic dotted-eighth echo at 120 BPM is 250 ms times 1.5 = 375 ms; set your delay to 375 ms and each repeat lands three sixteenths behind the note, creating that rolling, syncopated texture. You can also work backwards: if a 500 ms delay sounds right, then 60000 / 500 = 120 BPM, so it is already locked to the tempo.

Why beat duration matters

Beat duration in milliseconds is the bridge between musical time and machine time. For producers it makes time-based effects sit in the pocket: delays, tremolo and LFO rates, gated reverbs, and sidechain release times all sound tighter when their timing is derived from the tempo rather than guessed. For performers and arrangers it clarifies how fast a passage actually moves, which helps when setting a click, pacing a rehearsal, or matching two sections that should feel related. In teaching, converting BPM to milliseconds and to hertz gives students a tangible link between notation, the metronome, and the physics of sound. It also connects tempo to written tempo markings, so an Allegro or an Andante becomes a specific, testable number instead of a vague instruction.

Common pitfalls

A few traps are worth naming. The most common is treating the quarter note as the beat in every meter. In 4/4 that holds, but in 6/8 the felt beat is usually a dotted quarter, and in cut time (2/2) it is the half note, so read the note value against the time signature before trusting a figure. Remember, too, that BPM need not be a whole number; 128.5 BPM is perfectly valid and will shift every duration slightly. Finally, keep the notated tempo separate from the tempo you hear: a half-time or double-time feel can make a track seem twice or half as fast as its written BPM. Our note on rhythm versus tempo unpacks that distinction.

Sources: Grove Music Online, "Tempo" and "Metronome" (Oxford University Press); Roey Izhaki, Mixing Audio: Concepts, Practices, and Tools, 3rd ed. (Routledge/Focal Press, 2018), on tempo-based delay-time calculation; David Miles Huber and Robert E. Runstein, Modern Recording Techniques, 9th ed. (Routledge, 2017).