How to use
Enter the tempo and select the note symbol that the BPM marking counts. Then select the note value you want to time and whether it is regular, dotted, or one member of an even triplet.
The result is useful for practice timing, delay settings, animation cues, and checking written rhythms. It calculates duration only; it does not listen to audio or detect tempo.
Formula and beat-unit meaning
Duration = 60 ÷ BPM × (BPM beat denominator ÷ note denominator) × modifier. The modifier is 1 for a regular note, 1.5 for a dotted note, and 2/3 for a triplet member.
At quarter-note = 120 BPM, a quarter note is 0.5 seconds and an eighth note is 0.25 seconds. If the marking instead says dotted-quarter = 120, choose the closest available written beat only when that matches the intended convention; this tool does not model compound beat symbols.
Examples
Eighth note at quarter-note = 120 BPM
60 ÷ 120 × 4 ÷ 8 = 0.25 seconds, or 250 milliseconds.
Dotted quarter at quarter-note = 90 BPM
60 ÷ 90 × 4 ÷ 4 × 1.5 = 1 second.
Triplet eighth at quarter-note = 60 BPM
One regular eighth lasts 0.5 seconds; the triplet member lasts about 0.33 seconds.
Limits and common questions
- BPM describes the selected beat unit, not automatically the denominator of a time signature.
- Swing, rubato, fermatas, tuplets other than three, tempo ramps, and human timing are not modeled.
- Milliseconds are rounded for display while the calculation keeps full precision.
- For an entire song with measures and a time signature, use the music duration calculator.
Frequently asked questions
Does 120 BPM always mean a quarter note?
No. BPM counts the note symbol in the tempo marking. Quarter-note BPM is common, but another beat unit can be specified.
Why is a dotted note longer?
A dot adds half of the original value, so a dotted note lasts 1.5 times as long.