Metric Modulation Triplet Calculator

Metric Modulation Triplet Guide

1) Why Metric Modulation Works

Metric modulation lets you change tempo by redefining what a beat “means.” Instead of shifting by feel, you equate one rhythmic unit to another, so the transition is mathematically exact and repeatable.

2) Triplet Timing in Numbers

Triplets divide two equal beats into three notes. Each triplet note lasts 2/3 of its written value. If the base note is an eighth (1/8 of a whole), an eighth-note triplet is (2/3)×(1/8)=1/12 of a whole note.

3) What You Enter

Enter an old BPM and choose its reference note (quarter, half, etc.) plus dots. Then choose a triplet base note, dots, and whether you want a span of 1, 2, or 3 triplet notes. Finally, choose what new beat that span becomes, and set rounding for clean display.

4) How the Calculator Computes

The tool converts old BPM into seconds per old beat (60/BPM). It then scales to seconds per whole note by dividing by the old beat’s whole-note fraction. The triplet span is computed in whole-note units and converted back to seconds, then the new BPM is 60 divided by that span time.

5) Worked Example (120 BPM)

Old tempo: 120 BPM with quarter as the reference. A quarter at 120 lasts 0.5 s, so a whole lasts 2.0 s. One eighth-triplet is 1/12 of a whole, so it lasts 2.0/12=0.1667 s (166.7 ms). If that becomes the new quarter beat, new tempo is 60/0.1667 ≈ 360 BPM.

6) Using 2 or 3 Triplet Notes

Two eighth-triplets double the span: 0.3333 s (333.3 ms), giving a new quarter tempo of about 180 BPM. Three eighth-triplets equal two straight eighths (3×2/3=2), which often makes the modulation feel smoother because the full triplet group “resolves” into a clean duple duration.

Dots scale duration: dotted is 1.5× and double-dotted is 1.75×. Example: 72 BPM dotted quarter equals 108 BPM quarter, helping align the perceived pulse across the change.

7) Reading the Outputs

Besides new BPM, the calculator shows the modulation factor (new/old), the exact triplet span in milliseconds, and quarter-note equivalent BPM for both tempos. Use quarter-equivalent values to compare feels across different beat units, and use the millisecond span to verify accuracy against a click track during practice.

FAQs

1) What does this calculator actually match?

It matches a selected triplet span in the old tempo to a selected beat in the new tempo. The result is an exact tempo change, not an estimate.

2) What is the “triplet span count” option?

It lets you equate 1, 2, or 3 triplet notes to the new beat. Using 3 notes matches a full triplet group for clearer cues.

3) How do dotted notes affect results?

Dots extend note length by fixed fractions: dotted adds 50%, double-dotted adds 75%. A dotted reference beat at the same BPM lasts longer, so the computed new BPM adjusts.

4) Why show quarter-note equivalent BPM?

It converts both tempos to a common reference so you can compare feel across different beat units, like half-note beats versus quarter-note beats.

5) What if the new BPM is extremely high?

You likely matched a tiny triplet subdivision to a larger new beat. Try a larger triplet span (2 or 3 notes) or choose a smaller new beat value.

6) How can I rehearse the modulation cleanly?

Count the triplet subdivision, cue the exact span, then “name” it as the new beat. Practice with a metronome and verify the span in milliseconds for precision.