How to use the bpm to delay time calculator
- Enter the tempo in beats per minute, where one beat is a quarter note.
- Read the delay time for a quarter note, a dotted eighth note and an eighth note, and the length of one bar of 4/4.
- Use the table to find the delay in milliseconds for every note value from a whole note to a thirty-second note, in straight, dotted and triplet versions.
- The last column gives the repeat rate in hertz of an echo set to the straight value, useful for setting a modulation speed.
Formula
quarter note = 60,000 / BPM milliseconds
other note values: multiply by the number of beats the note lasts
dotted note = 1.5 x the straight note
triplet note = 2/3 x the straight note
repeat rate in Hz = 1,000 / delay in ms
A whole note is four beats, a half note is two, an eighth note is half a beat. The values assume the tempo does not change during the song.
120 BPM and 128 BPM
At 120 BPM a quarter note lasts 60,000 / 120 = 500 ms. An eighth note is 250 ms, a dotted eighth is 375 ms and an eighth-note triplet is 166.67 ms. A bar of 4/4 lasts 2,000 ms. The quarter note repeats at 2 Hz and the straight eighth note at 4 Hz.
At 128 BPM the quarter note is 468.75 ms and the dotted eighth is 351.56 ms. At 90 BPM a dotted quarter note is 1,000 ms, exactly one second. A delay set to a dotted eighth is a common choice because its repeats fall between the beats and fill the space without crowding them.
Why sync a delay to the tempo
An echo that repeats at a time unrelated to the beat sounds smeared. When the delay time equals a note value, the repeats land in time with the music. Many effects can sync to the host tempo by themselves. When yours cannot, this table gives the milliseconds to type in.
Finding the tempo and checking the setup
If you do not know the tempo of a track, tap along to it with the BPM Tap Counter. To check how much delay your audio interface adds on top of any effect, use the Audio Buffer Latency Calculator. A Metronome at the same tempo helps you check your timing.
More electronics and audio tools
For related electronics and audio work, try the Fret Position Calculator, ADC Resolution Calculator and RC Filter Time Constant Calculator.
Assumptions and limits
- A beat is a quarter note and the time signature has no effect on the milliseconds.
- The tempo stays the same through the song.
- The tempo must be between 1 and 999 beats per minute.
- The bar length shown is for 4/4 time.
- The tempo in the form is an example. Use the tempo of your own song.
Frequently asked questions
What is a dotted note?
A dot adds half the note's length again, so a dotted eighth note lasts as long as three sixteenth notes. That is why its delay is 1.5 times the straight eighth.
What is a triplet?
A triplet squeezes three notes into the time of two, so each lasts two thirds of the straight note. Triplet delays give a rolling, swung feel.
How do I turn the delay into a feedback rate?
Divide 1,000 by the delay in milliseconds to get repeats per second. A 500 ms delay repeats twice a second, which is 2 Hz.
Is 60,000 the same as the number of milliseconds in a minute?
Yes. A minute has 60 seconds and each second has 1,000 milliseconds, so dividing 60,000 by the beats per minute gives the milliseconds per beat.