BPM to milliseconds: delay times for every note value

One formula, and every note value falls out of it. The reason a dotted eighth is 375 ms at 120 BPM but 489 ms at 92 BPM is not that the two tempos are different — it is that a dotted eighth is always three quarters of a beat. Once that ratio is second nature, no preset value ever needs memorising.

The only formula you need

A tempo in beats per minute is a rate. A delay time is a duration. Converting between them is one division:

beat (ms) = 60000 ÷ BPM

Sixty thousand is the number of milliseconds in a minute. At 120 BPM one beat is 60000 ÷ 120 = 500 ms. Everything else is a ratio of that beat, and the ratios never change with tempo.

Note value	Fraction of a beat	At 120 BPM	At 92 BPM
Whole	4	2000.0 ms	2608.7 ms
Half	2	1000.0 ms	1304.3 ms
Quarter	1	500.0 ms	652.2 ms
Dotted quarter	1.5	750.0 ms	978.3 ms
Eighth	0.5	250.0 ms	326.1 ms
Dotted eighth	0.75	375.0 ms	489.1 ms
Sixteenth	0.25	125.0 ms	163.0 ms
Triplet eighth	1/3	166.7 ms	217.4 ms
Swung eighth	2/3	333.3 ms	434.8 ms

Read the last two columns together and the point becomes clear. A dotted eighth is 375 ms or 489 ms depending only on the tempo — the ratio is 0.75 either way. A preset labelled "dotted eighth" is only correct at the tempo it was set for, which is why a fixed delay that worked on one track can feel wrong on the next.

Dotted, triplet, swung: three different things

These three get confused constantly, and they are not variants of one another. A dotted value adds half again to the base: a dotted eighth is an eighth plus a sixteenth, three sixteenths in total, hence 0.75 of a quarter-note beat.

A triplet divides the beat into three equal parts, so a triplet eighth is 1/3 of a beat. It is uneven against the pulse, which is the whole point — that unevenness is what makes triplets feel like triplets.

A swung eighth also divides the beat in three, but distributes the unevenness the other way: the first note lasts two thirds and the second one third. At 120 BPM that is 333 ms then 167 ms. A triplet eighth gives 167 ms then 333 ms. Same three pieces of the beat, arranged in the opposite order, and the two feel completely different.

Working backwards

More often than not you have a delay time and want the tempo. That is the same division rearranged: multiply the delay by the fraction of a beat the note occupies to get the beat length, then divide 60000 by it.

BPM = 60000 ÷ (delay ms × beat fraction)

A 375 ms delay on a dotted eighth gives 375 × 0.75 = 281.25 ms per beat, and 60000 ÷ 281.25 = 120 BPM. The tool above shows this in the last row, which is the number to check when a preset sounds close but not quite right.

Why a fixed delay drifts

Here is the failure everyone hits eventually. A recorded tempo is never exactly constant. The drummer pushes, the song breathes, and the average tempo you measured is not the tempo in bar 32. A delay locked to a fixed millisecond value is therefore locked to the average, and it will be ahead of the grid in the busy bars and behind it in the slow ones.

This is why the tempo-synced modes in a DAW or a plug-in exist. Inside a host, the effect reads the timeline tempo and follows every change, so a tempo map with a ritardando at the end is simply honoured. A hardware unit, or any plug-in working in free-running milliseconds, has no such information and accumulates error.

The tap tempo readout on this page is a quick way to tell which situation you are in. If tapping along with a steady track produces a spread of a few BPM, the tempo is stable and a fixed delay will hold. If the readings wander, the track is pushing, and a fixed delay will drift no matter how carefully it is dialled in.

Five mistakes worth avoiding

1. Learning preset values instead of ratios. "Dotted eighth at 120 is 375 ms" is one fact. "Dotted eighth is 0.75 of a beat" is every fact.
2. Confusing triplet with swing. At 120 BPM the triplet eighth is 167 ms and the swung eighth is 333 ms. Swapping them turns a shuffle into a stumble.
3. Using a quarter note where a dotted quarter belongs. The difference is 50%, which is audible on every repeat.
4. Ignoring the tempo drift in a live take. A fixed delay set from the average tempo is the reason a loop that worked in rehearsal does not sit right in the take you kept.
5. Rounding a repeat to the nearest whole millisecond before dialling it in. A 1 ms error on a 500 ms delay is 0.2% — inaudible once, but it is also free not to commit.

Formulas worth keeping

Quantity	Expression
One beat	60000 ÷ BPM
Note value	beat ms × fraction
Dotted value	base × 1.5
Triplet value	base ÷ 3
Swung eighth	beat × 2/3
Tempo from delay	60000 ÷ (delay ms × fraction)
Repetition rate	1000 ÷ delay ms

Summary

Divide 60000 by the tempo, then multiply by a ratio: 1 for a quarter, 0.75 for a dotted eighth, 2/3 for a swung eighth, 1/3 for a triplet eighth. Work backwards by multiplying the delay by the ratio instead. Inside a DAW let the host handle the arithmetic so tempo changes are followed for free; outside one, understand that a fixed delay is locked to the average tempo and will drift on a take that breathes.

Common questions

The questions this page is most often asked, answered in full above.

What delay time should I use for a dotted eighth note?

A dotted eighth is 0.75 of a quarter‑note beat, so divide 60000 by the tempo and multiply by 0.75. At 120 BPM that is 375 ms; at 92 BPM it is 489 ms. The fraction does not change with tempo, which is why it is worth learning the ratio rather than memorising preset values.

How do I convert milliseconds back to BPM?

Multiply the delay time by the fraction of a beat the note occupies, then divide 60000 by that. A 375 ms dotted eighth gives 375 times 0.75 equals 281.25 ms per beat, so 60000 divided by 281.25 is 120 BPM. This is the calculation to use when a preset does not match the song.

What is the difference between a triplet delay and a swing delay?

Both divide the beat into three parts, but they distribute them differently. A triplet eighth makes the first note a third of the beat and the second two thirds, which is uneven. A swung eighth makes the first two thirds and the last one third, which is even but feels shuffled. At 120 BPM the triplet eighth is 166.7 ms and the swung eighth is 333.3 ms.

Why does my delay sound wrong even at the correct millisecond value?

Most likely the tempo is wrong, or the track drifts. A recorded tempo varies; if the drummer pushes, a fixed delay slowly falls out of sync with the eighth‑note grid. Free plugins that read the host tempo handle this automatically, while hardware units need the tempo dialled in accurately. The tap tempo readout on this page reports a stability figure that tells you which case you are in.

Should tempo‑synced effects use milliseconds or note divisions?

Use note divisions inside the DAW whenever possible, because they follow tempo changes automatically. Use milliseconds only for hardware, or when the delay is a fixed part of the sound rather than a rhythmic effect. Converting to milliseconds loses the relationship to the grid, so any later tempo change has to be corrected by hand.

Standards and references

Where the note-value ratios come from.

• Note value — the definition of each duration as a fraction of a whole note, which is the root of every number on this page.
• Tuplet — why a triplet divides by three and what "nested" tuplets mean when the value gets small.
• Sound On Sound — the practical articles on tempo mapping and drum timing that explain why live takes drift from any fixed value.