BPM to ms Calculator

How the BPM To Milliseconds Calculator works

BPM to ms: note lengths from tempo

Tempo in beats per minute and time in milliseconds are two descriptions of the same thing, and producers move between them constantly: setting a delay that repeats in time with the track, tuning a compressor's release to the groove, syncing an LFO or reverb pre-delay, or working out the length of a loop. The conversion is simple, 60,000 divided by the BPM gives the beat in milliseconds, but the dotted, triplet and subdivided values are fiddly enough that a table saves time.

The basic figure. At 120 BPM a beat lasts 500 ms, so a bar of 4/4 is two seconds, an eighth note is 250 ms and a sixteenth 125 ms. At 90 BPM the beat is 667 ms; at 174 BPM (drum and bass) it is 345 ms. The beat here is a quarter note, which is what BPM counts in almost all modern music, so a half-time feel or a 6/8 song still uses the quarter-note tempo in the DAW.

Dotted and triplet values. A dotted note is one and a half times its plain length; a triplet is two thirds of it. Dotted eighth delays (375 ms at 120 BPM) are the classic rhythmic delay sound, and triplet delays give a swung, shuffling repeat. The table lists both for every note value, so the dotted sixteenth or the triplet quarter is a single glance away.

Frequency for LFOs and tremolo. A repeating effect that cycles once per note has a frequency of 1,000 divided by the note's length in milliseconds. At 120 BPM a quarter-note LFO runs at 2 Hz and a bar-length sweep at 0.5 Hz. Many plugins let you sync to tempo directly, but hardware and older plugins take hertz, and the Frequency column gives the figure.

Converting a time back to a tempo. Enter a delay time in the second field to work the other way: a 400 ms delay is a quarter note at 150 BPM, an eighth note at 75 BPM or a sixteenth at 37.5 BPM. This is how you match a track to a preset delay time, or find the tempo of a loop whose length you know in milliseconds. Samples per beat at 44.1 and 48 kHz help when a sampler or editor shows positions in samples rather than time.

Compressor and reverb timing. A useful rule for a compressor on a rhythmic part is a release around the length of a sixteenth or eighth note so the gain has recovered by the next hit. For reverb, a pre-delay of a thirty-second note or so keeps the transient clear, and a decay of a bar or two fits the tempo. None of these are laws, but starting from a tempo-related figure and adjusting by ear is quicker than guessing.

BPM to milliseconds table

Straight note lengths in milliseconds. One beat is a quarter note.

Quarter, eighth, sixteenth note and one bar of 4/4 in milliseconds by tempo

BPM to ms formula and worked examples

The formula: quarter note (ms) = 60,000 ÷ BPM. An eighth is half that, a sixteenth a quarter, a dotted note × 1.5 and a triplet × 2/3. Frequency (Hz) = 1,000 ÷ ms.

First example. At 120 BPM a beat is 500 ms, an eighth 250 ms, a dotted eighth 375 ms and an eighth triplet 166.7 ms. As an LFO rate the beat is 2 Hz.

Second example. A 375 ms delay heard as a dotted eighth corresponds to 120 BPM; heard as a quarter note it would be 160 BPM.

How many samples per beat? Sample rate × ms ÷ 1,000: at 48 kHz and 120 BPM that is 24,000 samples.

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