Delay & Reverb Calculator
Enter your song's tempo and get reverb pre-delay and decay times that end on the grid for tight, room, hall and plate sizes, plus delay times for every note division.
Lead vocal, pads, strings
Pre-delay
62.5 ms
a 32nd note
Decay time
1938 ms
1 bar minus pre-delay
Total reverb
2000 ms
pre-delay + decay
Every reverb size at 120 BPM
| Size | Pre-delay | Decay | Total | Typical use |
|---|---|---|---|---|
| Tight ambience | 31.3 ms | 469 ms | 500 ms | Drums, percussion, rhythm guitar |
| Room | 31.3 ms | 969 ms | 1000 ms | Vocals in a mix, snare, keys |
| Hall | 62.5 ms | 1938 ms | 2000 ms | Lead vocal, pads, strings |
| Long / plate | 62.5 ms | 3938 ms | 4000 ms | Ballad vocal, ambient, transitions |
Delay times at 120 BPM
| Note | Straight | Dotted | Triplet |
|---|---|---|---|
| Half note (1/2) | 1000.0 ms | 1500.0 ms | 666.7 ms |
| Quarter note (1/4) | 500.0 ms | 750.0 ms | 333.3 ms |
| Eighth note (1/8) | 250.0 ms | 375.0 ms | 166.7 ms |
| Sixteenth (1/16) | 125.0 ms | 187.5 ms | 83.3 ms |
| Thirty-second (1/32) | 62.5 ms | 93.8 ms | 41.7 ms |
| Sixty-fourth (1/64) | 31.3 ms | 46.9 ms | 20.8 ms |
Beat = 60,000 ÷ 120 = 500.0 ms; bar = 2000 ms. Pre-delay is a 64th note for tight and room settings and a 32nd for hall and plate; decay is the chosen bar length minus the pre-delay, so the tail ends on the grid.
How the reverb times are built
The producer convention: total reverb length is a musical amount of time (a fraction of a bar or a whole bar or two), pre-delay is a short note value, and decay is what is left. That way the reverb tail dies exactly on a beat instead of smearing into the next one. The four sizes here are the common starting points; all four are derived from the beat length, 60,000 ÷ BPM, so they move together when the tempo changes.
Hall reverb decay at common tempos
| BPM | Tight ambience decay (ms) | Room decay (ms) | Hall decay (ms) | Long / plate decay (ms) |
|---|---|---|---|---|
| 80 | 703 | 1453 | 2906 | 5906 |
| 90 | 625 | 1292 | 2583 | 5250 |
| 100 | 563 | 1163 | 2325 | 4725 |
| 110 | 511 | 1057 | 2114 | 4295 |
| 120 | 469 | 969 | 1938 | 3938 |
| 128 | 439 | 908 | 1816 | 3691 |
| 140 | 402 | 830 | 1661 | 3375 |
| 150 | 375 | 775 | 1550 | 3150 |
| 170 | 331 | 684 | 1368 | 2779 |
Decay = bars × (240,000 ÷ BPM) − pre-delay. Tight and room use a 64th-note pre-delay; hall and plate a 32nd.
Choosing a size
Faster, denser songs want shorter tails, because there is less silence for the reverb to live in. A 170 BPM drum and bass track rarely wants more than a half-bar room on anything rhythmic; a 70 BPM ballad can carry a two-bar plate on the lead vocal without clouding. Set the size by the part's role: ambience on the rhythm section, room on supporting parts, hall or plate reserved for the one or two elements that should feel big. Then high-pass the reverb return around 200 to 300 Hz so the low end stays dry.
Frequently Asked Questions
How do I calculate reverb time from BPM?
Start with the length of a bar: 60,000 ÷ BPM × 4 for 4/4. Decide how long the reverb should hang, in bars: a quarter bar for a tight room, half a bar for a room, a full bar for a hall, two bars for a long plate. Subtract the pre-delay (a 64th or 32nd note) so the tail ends on a grid line. At 120 BPM a hall is a 2,000 ms bar minus a 62.5 ms pre-delay, giving a 1,937.5 ms decay.
What should pre-delay be set to?
Pre-delay is the gap before the reverb starts, which keeps the dry transient clear of the wash. A 64th note (31.25 ms at 120 BPM) suits drums and busy mixes; a 32nd (62.5 ms at 120) suits vocals and pads, where the extra separation makes the source sound closer and bigger at once. Anything over about 100 ms starts to read as a distinct slapback rather than a room.
Is a tempo-synced reverb always better?
No. It is a starting point that guarantees the tail clears before the next phrase, which is what you want on a rhythmic part. On a slow ballad vocal or an ambient pad, a longer, unsynced tail may sound better. Set the calculated value, then move the decay knob until the reverb breathes with the song rather than fighting it.
What delay time should I use?
Use the delay table under the reverb figures. Quarter-note and eighth-note delays sit on the beat and thicken a part; a dotted eighth (375 ms at 120 BPM) creates a syncopated echo pattern; a sixteenth (125 ms at 120) adds a tight double. Feedback controls how many repeats you hear, and the ms value is the spacing between them.
Does the time signature change the numbers?
Pre-delay does not, because it is a note value. Decay does, because it is expressed in bars: a bar of 3/4 is three beats, not four, so the same 'one bar' hall is 25% shorter. The calculator assumes 4/4; for 3/4 multiply the decay by 0.75, for 6/8 use the same as 3/4 at the dotted-quarter tempo.
These tools use the standard tempo, pitch and timing formulas (60,000 ÷ BPM, A4 = 440 Hz equal temperament, 1,200 cents per octave). They run in your browser; the tap counter uses your keyboard or mouse timing, so expect a beat or two of settling before the reading is stable.