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How to Set Delay Times in Time With a Track
Heshan Fernando
Co-founder & COO
A hardware delay pedal with a millisecond knob, a track at 120 BPM, and a part that needs the repeats to land in time. Guess and you’ll get close enough to sound almost right, which is worse than obviously wrong.
The conversion is one division, and the values worth knowing are a short list.
The arithmetic
A quarter note is sixty seconds divided by the tempo:
quarter note (ms) = 60,000 ÷ BPM
At 120 BPM that’s 500 ms. Everything else follows:
- Eighth note: half a quarter — 250 ms
- Sixteenth: 125 ms
- Dotted eighth: 1.5 × an eighth — 375 ms
- Eighth triplet: two-thirds of an eighth — 166.7 ms
For an LFO rate in hertz, invert the period: Hz = 1000 ÷ ms. A 500 ms cycle is 2 Hz.
Why the dotted eighth
Set a delay to a dotted eighth and the repeats fall between the eighth-note grid rather than on it. Against a straight eighth-note part, you get a cross-rhythm — a shifting pattern that sounds far busier than the notes being played.
It’s the sound behind a great deal of stadium rock guitar, and it works because it’s mathematically related to the tempo (so it locks in) but not aligned to it (so it creates movement). A straight eighth delay just thickens what’s already there.
| Note Value | Formula | At 120 BPM |
|---|---|---|
| Quarter | 60,000 ÷ BPM | 500 ms |
| Eighth | ÷ 2 | 250 ms |
| Dotted eighth | × 1.5 | 375 ms |
| Eighth triplet | × 2/3 | 166.7 ms |
| Sixteenth | ÷ 4 | 125 ms |
Where the table is actually needed
Most plugin delays sync to the host tempo automatically, so the table matters less than it used to. Where it still earns its place:
Hardware. Pedals and rack units with a millisecond knob and no sync.
Unsynced plugins. Some vintage emulations deliberately don’t sync.
Checking a synced unit. If a tempo-synced delay sounds wrong, knowing the expected millisecond value tells you whether the unit is doing what you think.
Pre-delay on reverb. Setting reverb pre-delay to a note value — often a sixteenth or a thirty-second — keeps the reverb’s onset rhythmic rather than smearing the transient.
Common mistakes to avoid
- Using the millisecond value from one section when the track has a tempo change.
- Setting a delay to a note value that doubles what the part is already playing, which just muddies it.
- Forgetting that analogue-modelled delays drift slightly from the exact value — that drift is often the point.
- Syncing everything rigidly, which removes the human feel that made the part work.
- Setting a long feedback on a dotted delay without checking it doesn’t build into mush.
How to do it with Note Length Table
The Note Length Table generates the full set of values for any tempo.
- Enter the track’s tempo.
- Read the value you need — quarter, eighth, dotted, or triplet.
- Enter the milliseconds into your delay, LFO or gate.
- For LFO rates, use the hertz column instead.
Other audio production tools are in the tools directory.
Frequently asked questions
Why is the dotted eighth used for delay so often?
Because its repeats fall between the eighth-note grid, creating a cross-rhythm against the beat rather than doubling it. It’s the sound behind a great deal of rhythmic guitar work.
How do I convert milliseconds to hertz for an LFO?
Divide 1000 by the length in milliseconds. A 500 ms cycle is 2 Hz, which is a quarter-note LFO at 120 BPM.
Does this matter with tempo-synced plugins?
Less, since they sync automatically. It matters for hardware, for plugins without host sync, and for checking that a synced unit is doing what you expect.
Final thought
Learn the quarter note formula and the two modifiers — 1.5 for dotted, two-thirds for triplet. That’s the entire table, derivable in your head at any tempo.