BPM to Hz: set an LFO rate without tempo sync

To make an LFO complete one cycle per quarter-note beat, divide BPM by 60. At 120 BPM, that is 2 Hz. For a different note division, first find the length of one complete cycle in milliseconds, then calculate 1,000 divided by that duration.

A matching rate determines how quickly the motion repeats. It does not automatically align the LFO’s peak with a kick or reset the waveform at the start of each bar. Frequency and phase are separate parts of the setup.

Convert a full cycle into hertz

Hertz means cycles per second. An LFO that takes half a second to complete its waveform runs at 2 Hz. One that takes two seconds runs at 0.5 Hz.

LFO frequency in Hz = 1,000 / full-cycle duration in ms
Full-cycle duration in ms = 1,000 / LFO frequency in Hz

The word full matters. For a sine wave, traveling from the lowest point to the highest point covers half a cycle. It then needs the other half to return to the same point moving in the same direction. Decide whether you want one complete rise-and-fall or only the rising part within a beat.

For one complete cycle per quarter note, substitute the beat duration 60,000 / BPM into the first formula. The result simplifies to BPM / 60. That shortcut applies to quarter-note cycles; other divisions need their own duration.

Common LFO rates at 120 BPM

Desired full-cycle length	Duration	LFO rate
One 4/4 bar	2,000 ms	0.5 Hz
Half note	1,000 ms	1 Hz
Quarter note	500 ms	2 Hz
Dotted eighth	375 ms	2.667 Hz
Eighth note	250 ms	4 Hz
Eighth-note triplet	166.667 ms	6 Hz
Sixteenth note	125 ms	8 Hz

Recurring values are rounded for display. The eighth-note triplet rate is exactly 6 Hz at 120 BPM when calculated from its unrounded duration. Use full precision during the conversion and round only to the resolution the device accepts.

For another tempo, read a duration from the BPM to MS calculator and divide 1,000 by that number. If the desired cycle spans several bars, multiply the appropriate bar duration before converting to frequency. In 4/4 at 120 BPM, two bars take four seconds, so one cycle over that span is 0.25 Hz.

Dotted cycles run slower; triplet cycles run faster

A dotted note lasts 1.5 times as long as its straight equivalent. Because frequency is the inverse of duration, its LFO rate is the straight rate divided by 1.5.

At 120 BPM, a straight eighth-note cycle runs at 4 Hz. A dotted eighth runs at 4 / 1.5, or approximately 2.667 Hz. Multiplying the frequency by 1.5 would make the motion faster, which is the opposite of the longer dotted duration.

An eighth-note triplet lasts two thirds of a straight eighth, so its frequency is 1.5 times the straight rate: 4 × 1.5 = 6 Hz. The note-division guide explains the duration ratios if you want to check why these frequency relationships reverse them.

Set the motion in a patch

Choose a simple waveform and a destination whose movement you can hear clearly, such as filter cutoff or volume. Keep modulation depth moderate while checking timing.

1. Set the LFO to a free-running rate mode labeled Hz, rather than a synced note mode.
2. Decide how long one complete waveform should take and calculate the frequency.
3. Enter the rate, then listen against a metronome or a simple drum pattern.
4. Adjust phase, reset, or retrigger controls if the correct-speed motion begins in the wrong place.
5. Restore the desired waveform and depth, then check how its audible accents sit against the track.

A ramp wave, a square wave, and a sine wave can create very different perceived accents at the same frequency. With volume modulation, polarity and depth also affect whether the loudest moment occurs at the point you expect. Judge alignment from the audible result, not just a moving graphic.

Why a correct rate can still drift

A free-running LFO may begin at an arbitrary point in its cycle. Starting playback again can therefore produce a different phase relationship unless the device follows transport or resets on a trigger. A note-retriggered LFO can restart with every played note, preventing the full cycle from unfolding during a busy phrase.

Manual Hz settings also do not follow a tempo change automatically. If the song moves from 120 to 128 BPM, a quarter-note rate should move from 2 Hz to approximately 2.133333 Hz. Use tempo sync when the device offers the behavior you need, or automate the rate with the tempo map.

Rounding can introduce smaller differences too. A device limited to two decimal places cannot represent every calculated rate exactly. For long passages where alignment matters, prefer a shared clock or reliable sync/retrigger mode. Use the conversion to choose the intended period, then let the device’s synchronization controls establish where that period starts.