For a constant musical tempo with the quarter note as one beat: milliseconds per beat = 60,000 ÷ BPM, pulse hertz = BPM ÷ 60, and BPM = 60,000 ÷ milliseconds per beat. For any repeating cycle lasting t milliseconds, Hz = 1,000 ÷ t and t = 1,000 ÷ Hz. Therefore 120 BPM = 500 ms per beat = 2 Hz, while a 100 ms cycle = 10 Hz. These are musical-timing and cycle-frequency conversions, not heart-rate or medical interpretations.

BPM to milliseconds and hertz chart

Quarter-note duration → pulse frequency, rounded to six decimals where needed: 100 BPM → 600 ms → 1.666667 Hz; 112 → 535.714286 ms → 1.866667 Hz; 120 → 500 ms → 2 Hz; 123 → 487.804878 ms → 2.05 Hz; 124 → 483.870968 ms → 2.066667 Hz; 127 → 472.440945 ms → 2.116667 Hz; 128 → 468.75 ms → 2.133333 Hz; 130 → 461.538462 ms → 2.166667 Hz; 150 → 400 ms → 2.5 Hz; 155 → 387.096774 ms → 2.583333 Hz; 160 → 375 ms → 2.666667 Hz; 180 → 333.333333 ms → 3 Hz. Dotted, triplet, and other note values scale the quarter-note duration; they do not change the source BPM.

Start with the quarter note

At 120 BPM, 60,000/120 equals exactly 500 ms. At 128 BPM it equals exactly 468.75 ms. The decimal BPM input is represented as a fraction before division, so a displayed rounded value never becomes the next input.

Scale written note values

A whole note is four quarter notes, a half is two, an eighth is one half, and each smaller binary division halves again. These are exact rational multipliers, independent of the displayed decimal precision.

Invert duration to get hertz

A cycle lasting t milliseconds repeats 1000/t times per second. Therefore a 500 ms quarter note is 2 Hz and a 250 ms eighth note is 4 Hz. This is cycle frequency, not audio pitch.

Keep the tempo contract visible

A score can define another beat unit, and a DAW can automate tempo. TempoCalc reports constant quarter-note timing. Time signature groups beats but does not change the duration formula by itself.