Converting BPM to milliseconds helps synchronize delay repeats, tremolo, gates, and other time-based audio effects with the music. The essential formula is quarter-note milliseconds = 60,000 ÷ BPM, assuming the BPM describes quarter-note beats. At 120 BPM, a quarter note lasts exactly 500 ms; an eighth note lasts 250 ms, and a sixteenth lasts 125 ms. Dotted and triplet variations follow simple musical ratios. You can perform these calculations manually or enter a tempo into our Delay & Reverb Calculator.
Why Convert BPM into Milliseconds?
Musicians describe timing in beats and note values, while many effect devices display time in milliseconds. If you want an echo to land every eighth note of a 120 BPM song, your delay should begin near 250 ms. Setting it by ear can be creative, but a calculated starting point gets you rhythmically aligned quickly. From there, you can adjust feedback, tone, wet/dry balance, or timing for the effect you want.
Tempo also provides useful references for an LFO's cycle rate and for rough starting values in reverb pre-delay and dynamics processing. These are starting points, not mandatory mixing settings. A beautiful delay can be intentionally off-grid, and a reverb tail may need shortening to avoid masking the next vocal phrase.
The Main BPM to MS Formula
Quarter-note duration (ms) = 60,000 / BPM
A minute contains 60,000 milliseconds. Divide that total by the number of quarter-note beats per minute to find the spacing between beats. For example, 60,000 ÷ 100 equals 600 ms per beat. At 150 BPM, the quarter-note interval is 400 ms. To work backward, use BPM = 60,000 / quarter-note milliseconds.
When a musical tempo marking uses a different beat unit, such as a dotted quarter in compound meter, establish the note-value relationship before treating the printed number as a quarter-note BPM. A tool that assumes quarter-note BPM should make that convention clear.
Note-Value Conversion Table at 120 BPM
| Note value | Straight | Dotted | Triplet |
|---|---|---|---|
| Whole note | 2,000 ms | 3,000 ms | About 1,333.33 ms |
| Half note | 1,000 ms | 1,500 ms | About 666.67 ms |
| Quarter note | 500 ms | 750 ms | About 333.33 ms |
| Eighth note | 250 ms | 375 ms | About 166.67 ms |
| Sixteenth note | 125 ms | 187.5 ms | About 83.33 ms |
| Thirty-second note | 62.5 ms | 93.75 ms | About 41.67 ms |
The table uses standard note-value fractions and assumes a steady 120 quarter-note BPM. A dotted value is 1.5 times the straight duration; a triplet note of a given nominal value is two-thirds of its straight duration because three triplet notes occupy the time of two straight notes of the same value.
How to Calculate Dotted Delay Times
A dot adds half the note's original length. At 120 BPM, a straight eighth note lasts 250 ms. Multiply that by 1.5 and the dotted-eighth delay is 375 ms. This spacing creates a familiar rhythmic offset against straight quarter and eighth notes. For guitar and synthesizer parts, a dotted-eighth pattern can leave room between new notes while the echoes add movement.
At 100 BPM, the quarter note is 600 ms, the eighth is 300 ms, and the dotted eighth is 450 ms. The formula works at any steady tempo: calculate the basic note length, then multiply by 1.5. You do not need a separate memorized table for every BPM.
How to Calculate Triplet Delays
Triplets divide the time of two normal notes into three equal notes. Multiply the straight note duration by 2/3. At 120 BPM, a triplet eighth note lasts approximately 166.67 milliseconds. Three eighth-note triplets together occupy one quarter-note beat, or 500 ms. This rhythmic subdivision is useful for shuffling echoes and phrases with a rolling feel.
Do not confuse a triplet note with a dotted note. A dotted eighth is longer than a straight eighth; an eighth-note triplet is shorter. Selecting the wrong subdivision can make repeats land in surprising places, which might be musically interesting but will not match the intended grid.
How to Sync Delay with a Song
First determine the song's tempo with the BPM Finder or use the BPM already confirmed in your DAW. Choose a note value based on the musical space you want. Quarter-note echoes have wider gaps; eighth-note echoes are more active; dotted eighths create offset rhythmic patterns; sixteenths make rapid, sometimes busy repeats. Enter the corresponding milliseconds in an effect that is not already tempo-synced.
Next reduce the feedback and wet level until the repeats support rather than compete with the original phrase. Listen to where the echoes fall relative to the snare and melody. The calculated time should act as a reliable reference point, but you may adjust by a few milliseconds for character or a particular performance.
How to Use BPM for Reverb Pre-Delay
Pre-delay is the gap between the dry sound and the onset of the reverb. A short pre-delay may create a sense of proximity, while a longer gap can keep the attack of a vocal or snare clear before the ambience arrives. Starting near a thirty-second, sixteenth, or eighth-note duration can help relate the space to the music, but the right value depends on the recording and reverb algorithm.
Reverb decay time is more complicated than a single note division. Different plugins may define decay as the time required for the sound to fall by a specified amount, commonly RT60, rather than the point of absolute silence. A two-beat decay can be a creative starting point, but it does not guarantee the tail will be inaudible at the next beat. Adjust decay by listening to the arrangement, tonal density, and available space.
Convert BPM to LFO Rate in Hertz
If a modulation control expects Hertz (cycles per second), use Hz = 1,000 ÷ period in milliseconds. A quarter-note cycle at 120 BPM lasts 500 ms, corresponding to 2 Hz. An eighth-note cycle lasts 250 ms and corresponds to 4 Hz. This provides a practical way to synchronize tremolo, auto-pan, or filter movement to the beat.
Note that many plugins can sync directly to your project's tempo, eliminating the need for manual input. A calculator remains useful with standalone pedals, older hardware, and effect interfaces displaying raw milliseconds or Hertz.
BPM, Bars, and Timing in Different Meters
At 120 BPM in 4/4, a four-beat bar lasts 2,000 ms. An eight-bar phrase lasts 16 seconds. In 3/4 at the same quarter-note pulse, a bar contains three quarter notes and lasts 1,500 ms. For 6/8, a bar contains six eighth notes, equal to three quarter-note durations, so it also lasts 1,500 ms when the underlying quarter-note rate is 120 BPM.
Musicians may feel 6/8 as two dotted-quarter pulses per bar, so make sure the tempo marking and calculator agree on the beat unit. Our BPM calculation tutorial shows how to convert between counting methods.
Frequently Asked Questions
How many milliseconds is 120 BPM?
A quarter-note beat at 120 BPM lasts 500 milliseconds. An eighth note lasts 250 ms, and a sixteenth note lasts 125 ms.
What is the dotted-eighth delay time at 120 BPM?
It is 375 milliseconds: a straight eighth note at 120 BPM is 250 ms, and a dotted note lasts 1.5 times as long.
Should reverb decay always match a note value?
No. Note divisions are useful musical starting points, but reverb decay depends on room simulation, plugin behavior, and the density of the mix. Adjust the actual tail by ear.
How do I calculate a triplet note from BPM?
Calculate the equivalent straight duration, then multiply by two-thirds. At 120 BPM, an eighth-note triplet is about 166.67 ms.
Is this formula accurate when the tempo changes?
It is exact for a constant tempo and specified beat unit. A tempo ramp changes beat length over time, so use automation or host tempo synchronization when appropriate.
Calculate now: Delay & Reverb Calculator. Learn more: What BPM means and How to Calculate BPM.
