Why sync delay and reverb to the tempo
A delay set to a note value of the song repeats in rhythm, so the echoes lock into the groove instead of blurring it. The same goes for reverb pre-delay and the rate of tremolo, auto-pan or filter LFOs. Most plugins have a sync button, but hardware pedals, older units and some reverbs still want a number in milliseconds or hertz. That's what this table gives you.
The formula
note (ms) = quarter note × length in quarter notes (whole = 4, eighth = 0.5 …)
dotted = note × 1.5 · triplet = note × 2/3
rate (Hz) = 1,000 ÷ note (ms)
BPM from a delay = 60,000 × length in quarter notes ÷ delay (ms)
There are 60,000 milliseconds in a minute, and BPM counts quarter-note beats per minute, so dividing one by the other gives the length of one beat.
Example: a song at 120 BPM
At 120 BPM a quarter note is 60,000 ÷ 120 = 500 ms, a dotted eighth is 375 ms and one bar of 4/4 is 2,000 ms. Here is the full set of note lengths in milliseconds:
| Note | Straight | Dotted | Triplet |
|---|---|---|---|
| 1/1 (whole) | 2,000 | 3,000 | 1,333.3 |
| 1/2 (half) | 1,000 | 1,500 | 666.7 |
| 1/4 (quarter) | 500 | 750 | 333.3 |
| 1/8 (eighth) | 250 | 375 | 166.7 |
| 1/16 (sixteenth) | 125 | 187.5 | 83.33 |
| 1/32 (thirty-second) | 62.5 | 93.75 | 41.67 |
In hertz, the quarter note is 1,000 ÷ 500 = 2 Hz and the eighth note is 4 Hz.
Tips for tempo-synced effects
- Dotted eighth for guitar. Play straight eighths against a dotted-eighth delay and the repeats fill the gaps between your notes.
- Quarter or eighth for vocals. A quarter-note slapback-style repeat, mixed low and filtered, adds depth without cluttering the lyric.
- Short pre-delay keeps vocals clear. A 1/32 or 1/64 note of pre-delay lets the dry word speak before the reverb arrives.
- Round to taste. A millisecond or two either way is inaudible; set the time slightly shorter if the repeats feel like they drag.
Frequently asked questions
How do I calculate delay time from BPM?
Divide 60,000 by the BPM to get one quarter note in milliseconds. At 120 BPM that's 500 ms. Halve it for an eighth note (250 ms), double it for a half note (1,000 ms), multiply by 1.5 for dotted notes and by 2/3 for triplets.
What is a dotted eighth delay?
A dotted eighth note is three sixteenths long, or 0.75 of a quarter note. At 120 BPM it's 375 ms. Set against straight eighth-note playing, the repeats fall between your notes, which creates the rhythmic, cascading guitar delay sound heard in a lot of rock and worship music.
Why convert note lengths to Hz?
Hertz is cycles per second, which is how many tremolo, auto-pan, filter or chorus LFOs set their rate. Hz = 1,000 ÷ milliseconds, so a quarter note at 120 BPM is 2 Hz: the LFO completes two full cycles every second, one per beat.
How do I set reverb pre-delay to the tempo?
Pick a short note value, often a 1/32 or 1/64 note, so the reverb starts just after the dry sound in time with the groove. At 120 BPM a 1/32 note is 62.5 ms. Some engineers also time the reverb's decay to end around a half or whole note so the tail clears before the next phrase.
How do I find the BPM of a delay time?
Divide 60,000 by the delay in milliseconds to get the BPM if that delay is a quarter note. If it's an eighth note, divide 30,000 instead; for a dotted eighth, divide 45,000. Use the delay time mode above and pick the note value.
Rates and figures last checked October 2026.
This calculator gives estimates for planning. Check current rates and product labels before you buy, list or file.