Delay and Reverb Time Calculator
A quarter note lasts 60,000 / BPM ms. At 120 BPM that is 500 ms, an eighth note is 250 ms, a dotted eighth is 375 ms and an eighth-note triplet is 166.7 ms. A 1/64-note pre-delay is 31.25 ms.
How to use
- Enter the tempo of your song in BPM, or tap the Tap button in time with the music and the BPM fills in for you.
- Read the delay time you need from the table: pick the note value (1/1 to 1/64) and the column for straight, dotted or triplet. Switch between ms and Hz at the top.
- For reverb, take the pre-delay and decay for a room, large room or hall from the second table, and type them into your reverb plugin.
- To go the other way, enter a delay time in ms under "ms to BPM", choose the note value, and read the tempo it matches.
How it works
A quarter note lasts 60,000 / BPM milliseconds. At 120 BPM that is 500 ms. Every other note value follows from it: 1/n note = 240,000 / (BPM × n) ms, so each step down (1/4, 1/8, 1/16 ...) is exactly half as long.
A dotted note is 1.5 times the straight value (a dotted 1/8 at 120 BPM is 375 ms). A triplet is 2/3 of the straight value (an 1/8 triplet is 166.7 ms). Frequency is Hz = 1000 / ms, so 500 ms is 2 Hz.
Reverb pre-delay is a note value: 1/64 for a small room and 1/32 for a larger one. At 120 BPM that is 31.25 and 62.5 ms. Decay is the tail length minus the pre-delay, where the tail is a half note (small room), one bar of 1/1 (large room) or two bars (hall).
These reverb sizes are mixing rules of thumb, not a standard. Engineers such as Bobby Owsinski name 20 to 40 ms as the most common pre-delay, and tempo calculators map a small room to a half note, a large room to one bar and a hall to two bars. Every reverb plugin decays a little differently, so adjust by ear.
Going back: BPM = 240,000 × factor / (ms × n), where the factor is 1 for straight, 1.5 for dotted and 2/3 for triplet. A 375 ms delay is a dotted 1/8 at 120 BPM.
FAQ
How do I convert BPM to milliseconds?
Divide 60,000 by the BPM. That gives the length of a quarter note in ms: 120 BPM is 500 ms, 90 BPM is 666.7 ms. Halve it for an eighth note, double it for a half note.
What is a dotted or triplet delay time?
A dotted note is 1.5 times longer than the straight note, so a dotted 1/8 at 120 BPM is 375 ms. A triplet is 2/3 as long, so an 1/8 triplet is 166.7 ms. Dotted eighth delays are a classic rhythmic echo.
What pre-delay should I use for reverb?
A common starting point is 20 to 40 ms, which is roughly a 1/64 to 1/32 note at 120 BPM. A short pre-delay keeps the sound close, a longer one separates the dry vocal or snare from the tail. Trust your ears.
How long should the reverb decay be?
To keep it in time, make the tail die out by the next beat, half bar or bar. Here a small room is a half note, a large room one bar and a hall two bars, each minus the pre-delay. Slow songs need longer tails in ms.
Why show Hz as well as ms?
Delay time as a frequency is useful for modulation rates, LFO speed and for comparing a delay with a comb-filter pitch. Hz is 1000 divided by ms.
Does this work for any BPM?
Yes, from 20 to 400 BPM, including decimals such as 127.5. Tap the button in time with a song to measure the tempo first.