BPM to ms
Tempo to delay, reverb pre-delay and tempo-synced times in milliseconds. Tap tempo for live detection, or work back from a delay time to the tempo behind it.
Tempo
Note values
| Note value | Milliseconds |
|---|
Milliseconds to tempo
Tempo-Synced Reverb Pre-Delay
Sound reaches a listener in stages: a direct-path arrival, then a cluster of early reflections from nearby surfaces, then a dense, statistically random late reverberation that forms the decaying tail. Reverberators are commonly built to mirror this structure: a short early-reflections stage with its own timing, followed by a separate late-reverberation stage. Pre-delay times the start of that late stage relative to the early reflections; it is a gap inserted before the diffuse tail begins, not a delay applied to the early reflections themselves.
Early reflections keep their own timing, set by the space being simulated. They arrive between the direct sound and the diffuse tail and convey a sense of the space's size and surfaces. Pre-delay does not add, remove, or reposition them. It only moves when the diffuse tail starts.
Widening that gap separates the direct sound and the early reflections in time from the diffuse tail, so the source is heard more distinctly on its own before the reverb's wash arrives; this is how engineers make a source read as more upfront and present. Narrowing the gap toward zero pulls the diffuse tail's onset close enough to the direct sound to fall inside the ear's fusion window, where the two are heard as one glued event rather than two separate arrivals, so the source reads as embedded in the reverb rather than separated from it.
Note Value to Milliseconds
ms per quarter note = 60000 / BPM
note value ms = (60000 / BPM) × ratio
ratios: quarter = 1 eighth = 0.5 sixteenth = 0.25 thirty-second = 0.125
example @ 120 BPM:
1/16 = (60000 / 120) × 0.25 = 125 ms
1/32 = (60000 / 120) × 0.125 = 62.5 ms- 0–20 ms: mostly falls inside the ear's perceptual fusion window (roughly a few milliseconds for transient, click-like sounds, extending toward about 40 ms for more complex signals such as speech): reflected or reverberant energy arriving this soon after the direct sound is heard as one glued event with it, not as a separate arrival. This tightens the source into the reverb rather than isolating its attack.
- 20–80 ms and above: moves toward and beyond the upper edge of that fusion window for most program material, so the diffuse tail becomes increasingly distinct from the direct sound; the source separates from, rather than being pushed back by, the reverb.
- Syncing to a note value: places the diffuse tail's onset on the tempo grid; the specific value is a creative choice, not something dictated by the fusion-window range above.
- Same math, tempo-synced delays: the 60000 / BPM × ratio calculation applies directly to synced delay times.
Frequently Asked Questions
What is reverb pre-delay?
Pre-delay is the gap between the direct sound and the onset of the reverb's diffuse tail, the dense late-reverberation stage that follows the early reflections. It times when that tail begins; it is not applied to the early reflections themselves, which keep their own timing.
Why sync reverb/delay times to tempo?
Syncing the diffuse tail's onset, or a delay's repetition, to a note value places those onsets on the tempo grid, so the reverb or echo feels musically related to the track rather than drifting against it.
How do I convert a note value to milliseconds?
Use ms per quarter note = 60000 / BPM, then multiply by the note's ratio: quarter = 1, eighth = 0.5, sixteenth = 0.25, thirty-second = 0.125. At 120 BPM, 1/16 = (60000 / 120) × 0.25 = 125 ms and 1/32 = (60000 / 120) × 0.125 = 62.5 ms.
What note value should I use for pre-delay?
A longer pre-delay (for example 1/32 or 1/16 of a beat, or larger) widens the gap toward and beyond the ear's fusion window, so the direct sound is heard more distinctly before the diffuse tail arrives. A shorter or zero pre-delay keeps the gap inside that fusion window, so the diffuse tail is heard as glued to the direct sound rather than separate from it.
Does pre-delay change the reverb's character or just its timing?
Pre-delay affects timing only: it shifts when the diffuse tail begins relative to the direct sound and early reflections. It does not change the reverb's decay rate, tonal colour, or the early reflections' own timing.
Can I use this for slapback and echo too?
At around 120 BPM, slapback and single-echo times in the 60–120 ms range roughly correspond to a 1/32 to 1/16 note. At other tempos, use 60000 / BPM × ratio to land the repeat in that window.