Calculate straight, dotted and triplet note lengths. It is designed for composers, MIDI editors and sound designers translating notation into exact time.
The calculation in one line
Use durations for envelopes, gates and modulation, but leave articulation room so consecutive notes do not always overlap.
Worked example
At 120 BPM an eighth is 250 ms, dotted eighth 375 ms and eighth-note triplet approximately 166.67 ms.
Does note duration equal gate length?
Not necessarily. Written duration defines a rhythmic span; performed articulation may occupy only part of it. A staccato eighth can use a short gate inside the full eighth-note slot, while legato notes may overlap.
Three checks before using the answer
- Select the written subdivision first.
- Apply dotted or triplet modification only once.
- Leave release time before the next critical attack.
A detail that changes the interpretation
Swing changes the paired subdivision ratio. Two swung eighths are not necessarily equal halves even though the beat duration remains unchanged.
Most common mistake
Applying the triplet factor to the wrong straight value. An eighth-note triplet is two-thirds of a straight eighth, not a quarter.
Where the calculation stops
Written duration and performed duration differ when articulation, swing, human timing or tempo changes are present.
Research note
The calculation provides grid duration, while performance and MIDI articulation remain separate decisions. Read Apple’s Logic Pro tempo overview. External documentation supports the technical context; its publishers do not endorse PulseKit.
Questions musicians ask
Who is this note duration calculator for?
It is intended for composers, MIDI editors and sound designers translating notation into exact time.
What should I listen for after calculating?
Use durations for envelopes, gates and modulation, but leave articulation room so consecutive notes do not always overlap.
Can the result be technically correct but musically wrong?
Yes. Written duration and performed duration differ when articulation, swing, human timing or tempo changes are present.
Inputs stay on this device. Display rounding never changes the underlying formula.