BPM Tempo Converter
Calculate the duration in milliseconds of any musical note value at a given BPM and time signature. Use this when programming delay times, sequencer steps, or syncing effects to the tempo of a track.
About this calculator
Musical tempo is measured in beats per minute (BPM). The duration of a single beat (one quarter note in 4/4 time) is 60,000 ms / BPM. To find the duration of any other note value, you scale this beat duration by the ratio of the desired note length to a quarter note, and then account for the time signature. The formula used here is: Duration (ms) = (60000 / BPM) × (4 / noteValue) × (timeSignatureTop / timeSignatureBottom). The factor (4 / noteValue) scales from a quarter-note reference: a half note (noteValue = 2) lasts twice as long, a sixteenth note (noteValue = 16) lasts one-quarter as long. The time signature factor adjusts the result proportionally to the meter's beat grouping, allowing calculations in compound and irregular meters.
How to use
Find the duration of a dotted eighth note equivalent in a track at 120 BPM in 4/4 time, using noteValue = 8 and timeSignature 4/4. Step 1: 60,000 / 120 = 500 ms per beat. Step 2: multiply by (4 / 8) = 0.5 → 500 × 0.5 = 250 ms (one eighth note). Step 3: multiply by (4 / 4) = 1 → 250 × 1 = 250 ms. So an eighth note at 120 BPM lasts 250 ms. For a quarter note in 6/8 at 90 BPM: (60,000 / 90) × (4 / 4) × (6 / 8) = 666.67 × 1 × 0.75 ≈ 500 ms.
Frequently asked questions
How do I set my delay time in milliseconds to sync perfectly with the tempo of my track?
Divide 60,000 by your BPM to get the duration of one quarter-note beat in milliseconds. For a tempo of 128 BPM, one beat = 60,000 / 128 ≈ 468.75 ms. For an eighth-note delay, halve that value to ≈ 234.38 ms; for a dotted quarter, multiply by 1.5 to get ≈ 703.13 ms. Setting your delay time to these values ensures each echo lands exactly on a rhythmic subdivision, creating a tight, musical effect rather than a cluttered, off-beat trail.
What does the note value field represent and which numbers should I enter?
The note value field represents the denominator of a musical note relative to a whole note. Enter 1 for a whole note, 2 for a half note, 4 for a quarter note, 8 for an eighth note, 16 for a sixteenth note, and 32 for a thirty-second note. Dotted notes can be approximated by multiplying the result by 1.5 after calculation, since a dotted note lasts 1.5× its base value. Triplet notes divide a beat into three equal parts, so a quarter-note triplet would use a note value of 6 (three triplet quarters per half note).
How does the time signature affect the calculated note duration?
The time signature factor (timeSignatureTop / timeSignatureBottom) scales the output to reflect the metric grouping of the piece. In straightforward 4/4 time this ratio equals 1, leaving the duration unchanged. In 6/8 time the ratio is 6/8 = 0.75, shortening durations relative to 4/4 at the same BPM. This adjustment is useful when calculating bar-length or phrase-length durations in unusual meters. For standard delay and LFO tempo-sync applications in 4/4, you can leave top and bottom both at 4, but the field becomes critical when working in 3/4, 5/4, 7/8, or other irregular time signatures.