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Music Calculator: BPM, Delay & Notes
Tap a tempo, turn BPM into delay and reverb times, note names into frequencies, and look up scales and chords.
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Delay times
| Note | Straight | Dotted | Triplet |
|---|
Reverb suggestions
| Space | Pre-delay | Decay | Total |
|---|
Each suggestion makes pre-delay plus decay fill a note length, so the tail dies away in time with the song. Treat them as a starting point and trust your ears.
Note to frequency
A letter, an optional # or b, and an octave: A4, C#3, Bb2.
Frequency to note
Delay times are rounded to two decimal places of a millisecond. Notes use equal temperament from the reference A4 you set, with MIDI numbering where middle C is C4. Notes are spelt from the scale or chord degree, so you will see both sharps and flats.
How to use it
- Tap tempo: tap the big button in time with a song to measure its BPM, then send it to the delay tab.
- Delay and reverb: type a tempo to see every note length in milliseconds and hertz, with dotted and triplet values, and reverb settings that fit the tempo.
- Notes and scales: convert between note names and frequencies, or pick a root and a scale or chord to list and hear its notes.
Questions
How is a delay time worked out from BPM?
One beat, a quarter note, lasts 60,000 divided by the BPM in milliseconds: 500 ms at 120 BPM. Halve it for an eighth note, double it for a half note. A dotted note is one and a half times as long, a triplet two thirds as long.
Why show the time in hertz?
Modulation effects such as tremolo, auto pan and filter sweeps set their speed as a rate in hertz. The hertz value is one second divided by the note length, so the effect cycles once per note.
What is cents in the frequency result?
A cent is a hundredth of a semitone. The result shows how far your frequency is above or below the nearest note, from minus 50 to plus 50 cents.
Why is the same note sometimes called D# and sometimes Eb?
Notes in a scale or chord are named from their degree: in B major the third is D#, while in C minor it is Eb, even though both are the same key on a piano.
About this tool
About the music calculator
Producers, players and sound engineers keep running into the same small sums: what tempo is this song, how long should the delay be, what frequency is that note. This calculator gathers them in four tabs.
Tap tempo
Tap the big button in time with a song to measure its BPM, then send the result to the delay tab.
Delay and reverb
Type a tempo to see every note length in milliseconds and hertz, including dotted and triplet values, plus reverb pre-delay and decay settings that sit with the tempo. One quarter note lasts 60,000 divided by the BPM, so 500 ms at 120 BPM; halve it for an eighth, and multiply by one and a half for a dotted note. The hertz figures suit tremolo, auto-pan and filter effects that set their rate as a frequency, so they cycle once per note.
Notes and Hz
Convert a note name to its frequency or a frequency to the nearest note, with how many cents it sits above or below, from minus 50 to plus 50. Notes use equal temperament from the A4 reference you set, and middle C is C4.
Scales and chords
- Pick a root and a scale or chord type to list its notes and hear them.
- Notes are spelt from their degree, so B major shows D# while C minor shows Eb, even though both are the same piano key.
Everything is calculated and played in your browser.
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