LFO Tempo Sync Calculator
A low-frequency oscillator drives tremolo, auto-pan, filter sweeps, and wobble effects, and it sounds tightest when its cycle lines up with the beat. To sync it, choose how many beats one LFO cycle should last, then convert to a rate in hertz: the tempo over 60, divided by the beats per cycle. This calculator takes your tempo and the beats per cycle (one beat for a quarter note, half a beat for an eighth, four beats for a 4/4 bar) and returns the LFO rate in hertz along with the cycle period in seconds and milliseconds. Dial those into your synth or effect to lock modulation to the groove.
LFO sync formula
Beat frequency = BPM / 60 (Hz)
LFO rate = beat frequency / beats per cycle (Hz)
Cycle period = 1 / LFO rate (seconds)
Period in ms = cycle period * 1000
Beats per cycle sets the note division: 1 for a quarter note, 0.5 for an eighth, 0.25 for a sixteenth, 4 for a bar in 4/4. Cycles per minute equals 60 times the rate.
Modulation sync context
- At 120 BPM a quarter-note cycle is a 2 Hz LFO; a whole-bar cycle is 0.5 Hz.
- Wobble bass often uses eighth or sixteenth cycles; slow sweeps use a bar or more.
- Halving beats per cycle doubles the LFO rate; one octave faster modulation.
- Set the rate, period, or note value depending on what your effect exposes.
- Synced modulation keeps peaks and troughs on the beat for a tight feel.
LFO sync: frequently asked questions
How do I sync an LFO to tempo?
Decide which note division you want one LFO cycle to last, expressed in beats. A quarter note is one beat, an eighth is half a beat, a whole bar in 4/4 is four beats. The LFO rate in hertz is the tempo divided by 60, divided by that number of beats per cycle.
What note division should one LFO cycle span?
It depends on the effect. A slow filter sweep might span a whole bar (four beats), a wobble bass an eighth or sixteenth, and a tremolo a quarter or eighth. Set the beats-per-cycle input to the division you want and read off the matching rate.
What is the difference between rate and period?
Rate is how many cycles happen per second, in hertz. Period is how long one cycle lasts, in seconds or milliseconds, and is simply one divided by the rate. Some LFOs are set by rate, others by period or by a note value; this calculator gives both.
Why does a synced LFO sound tighter?
When the LFO cycle lines up with a musical subdivision, the modulation peaks and troughs land on the beat, reinforcing the groove. A free-running LFO drifts in and out of phase with the music, which can sound loose or unsettled for rhythmic effects.
Can I use this for tremolo and auto-pan too?
Yes. Tremolo, auto-pan, phaser sweep, and filter modulation are all LFO-driven. Set the beats-per-cycle to the rhythm you want the effect to pulse at, and use the resulting rate or period in your plugin or pedal.
Official sources
- UNSW School of Physics: Music acoustics.
- MIDI Association: MIDI tempo and timing specification.
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.