Reverb Pre-Delay Calculator

Tempo-synced pre-delay and decay times for a hall, a large or small room and a tight ambience, so the reverb tail clears before the next hit.

Updated October 13, 2026 · By Niraj Kumar

Tempo

BPM

↑ ↓ nudge by 1, with Shift by 0.1. One beat = 500 ms.

Reverb pre-delay & decay

Hall1/64 + tail to 2 bars

Pre-delay
Decay
Total

Large room1/128 + tail to 1 bar

Pre-delay
Decay
Total

Small room1/256 + tail to 1/2

Pre-delay
Decay
Total

Tight ambience1/512 + tail to 1/4

Pre-delay
Decay
Total

A starting point: shorten the decay until the tail stops masking the next phrase.

Delay times · click to copy

Note	Straight	Dotted	Triplet
2 bars
1/1 (bar)
1/2
1/4
1/8
1/16
1/32
1/64

Bar & sample length

Time signature

Bars

Sample rate

Milliseconds

Seconds

Samples

Delay time → BPM

Delay time

Heard as

Feel

120 BPM

How do you calculate reverb pre-delay from tempo?

Set the pre-delay to a short note value and the decay so the tail ends on a musical boundary. At 120 BPM a hall gets 31.25 ms pre-delay (a 1/64 note) and 3,968.75 ms decay to fill 2 bars; a small room 7.81 ms and 992.19 ms to fill a half note.

quarter note (ms) = 60 000 ÷ BPM;  note = quarter × q;
dotted = note × 1.5;  triplet = note × 2/3;  rate (Hz) = 1000 ÷ ms;
bar = quarter × beats × 4 ÷ unit;  samples = seconds × sample rate

This page uses the same method as the BPM to MS Calculator, which explains each term and assumption in full.

Tempo-synced reverb times at common tempos (pre-delay / decay, ms)
BPM	Hall	Large room	Small room	Tight ambience
70	53.57 / 6,803.57	26.79 / 3,401.79	13.39 / 1,700.89	6.7 / 850.45
90	41.67 / 5,291.67	20.83 / 2,645.83	10.42 / 1,322.92	5.21 / 661.46
100	37.5 / 4,762.5	18.75 / 2,381.25	9.38 / 1,190.63	4.69 / 595.31
120	31.25 / 3,968.75	15.63 / 1,984.38	7.81 / 992.19	3.91 / 496.09
128	29.3 / 3,720.7	14.65 / 1,860.35	7.32 / 930.18	3.66 / 465.09
140	26.79 / 3,401.79	13.39 / 1,700.89	6.7 / 850.45	3.35 / 425.22
174	21.55 / 2,737.07	10.78 / 1,368.53	5.39 / 684.27	2.69 / 342.13

Worked example

A vocal at 120 BPM that sounds muddy under a long hall reverb, to be reset in time with the song.

1One beat: 60,000 ÷ 120 = 500 ms
2Hall: pre-delay 1/64 = 31.25 ms; total 2 bars = 4,000 ms; decay 4,000 − 31.25 = 3,968.75 ms
3Large room: pre-delay 1/128 = 15.63 ms; total 1 bar = 2,000 ms; decay 2,000 − 15.63 = 1,984.38 ms
4Small room: pre-delay 1/256 = 7.81 ms; total 1/2 = 1,000 ms; decay 1,000 − 7.81 = 992.19 ms
5Tight ambience: pre-delay 1/512 = 3.91 ms; total 1/4 = 500 ms; decay 500 − 3.91 = 496.09 ms

For the vocal, try the large room: 15.63 ms pre-delay and 1,984.38 ms decay, so the tail ends on the next bar line.

Frequently asked questions

What does reverb pre-delay do?

It holds back the start of the reverb for a few milliseconds after the dry sound. The ear hears the consonants and attack clearly first, then the space, so a vocal keeps its intelligibility and stays in front of the mix while still sounding big. Pre-delay is also a size cue: longer pre-delay suggests a larger room with more distant walls.

Are these decay times exact rules?

No, they are a starting point. Decay or RT60 is the time for the reverb to fall by 60 dB, and plugins measure it differently, so a 2-second setting on two units will not sound identical. Start from the suggested time, then shorten it until the tail stops masking the next phrase. Dense mixes and fast tempos want shorter tails than these.

How much pre-delay should vocals have?

Commonly 20 to 80 ms: enough to separate the reverb from the voice, not so much that it sounds like an echo. At 120 BPM a 1/64 note is 31.25 ms and a 1/32 note 62.5 ms, both in that range. At slow tempos the 1/64 note grows longer; check that it still sounds like one event.