BPM Calculator
Tap in beats and elapsed time to get the tempo, plus every note value in milliseconds.
Last updated · View algorithm, constants and default inputs (JSON)
About this calculator
Tempo is beats divided by time, and the note values follow from the beat length. This calculator treats each counted beat as a quarter note; compound-meter pulse conventions are not modeled. At 120 BPM, a quarter note lasts half a second.
Worked example
calculated with the default values below
Number of beats 32 · Elapsed time 16 seconds · Beats per bar 4 Tempo 120.00 BPM · Quarter note 500.00 ms · One bar 2,000.00 ms · Eighth note 250.00 ms · Sixteenth note 125.00 ms · Half note 1,000.00 ms · Whole note 2,000.00 ms · Tempo marking Allegro
General background references
Disclaimer
These calculators give general estimates. Sizing, pricing, availability and standards vary by brand, retailer and country, so treat the output as a starting point and confirm it against the seller's or authority's own figures.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
BPM = 60·B/s; ms = 60000/BPM
- B
- Beats counted
- s
- Counting time (seconds)
- BPM
- Beats per minute
- ms
- Milliseconds per beat
Tempo words are approximate labels. Bar duration = beat duration × beats per bar; other note values scale by their stated multiples.
Frequently asked questions
Why is a quarter note exactly half a second at one hundred twenty BPM?
Tempo in BPM is beats per minute, so at 120 BPM one beat lasts 60,000 divided by 120, or 500 milliseconds; with four beats per bar a bar is 2,000 ms. The tool derives every other note by dividing or multiplying that beat, an eighth note is 250 ms, a sixteenth 125 ms, a whole note 2,000 ms. The tempo marking at 120 reads Allegro, since the scale shifts at fixed BPM boundaries like 108 and 156. The Italian tempo word is an approximate range label.