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Musical Note Frequency Generator

DataMath

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INPUT

Auto Process

Mode

Convert

Tuning Reference

A4 Reference

Reference Hz (A4)

Auto-fills from preset; edit to use a custom reference.

Note Input

Note

Octave

Frequency Input

Frequency (Hz)

Enter any audible frequency; the nearest note will be detected.

Playback Controls

Waveform

Volume %: 30

Duration (ms): 800

OUTPUT

Client Side

Result

Note

Frequency

MIDI Note

Wavelength (air, 20°C)

Cents Offset

Interactive Piano

Click any key to play the tone and pick that pitch as the current note.

Octave Reference

All 12 notes in the selected octave with their frequency, MIDI number, and wavelength.

Note	Frequency	MIDI	Wavelength
C
C# / Db
D
D# / Eb
E
F
F# / Gb
G
G# / Ab
A
A# / Bb
B

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Guide

Musical Note Frequency Generator

Convert any musical note to its exact frequency in hertz, MIDI note number, and wavelength — or go the other way and find the nearest note for any frequency you enter. An interactive piano keyboard lets you click any key to hear the tone through your browser, and you can switch the tuning reference between modern (A4 = 440 Hz), Verdi (432 Hz), modern orchestral (444 Hz), and Baroque (415 Hz) pitches.

How to Use

Pick the conversion direction — Note → Frequency or Frequency → Note.
Choose a tuning reference (440 Hz is the modern standard) or type a custom A4 value.
For note mode: pick the note name and octave. For frequency mode: enter any frequency in hertz.
Read the results: note name, frequency, MIDI number, and acoustic wavelength.
Click the on-screen piano keyboard to audition any pitch, or hit Play Tone to hear the current selection.

Features

Bidirectional conversion – Note + octave to frequency, or any Hz to the nearest equal-tempered note with cents offset.
Interactive piano keyboard – Three octaves centered on your current selection; click any key to play it.
Web Audio playback – Sine, triangle, square, and sawtooth waveforms with adjustable volume and duration.
Multiple tuning standards – 440 Hz (modern), 432 Hz (Verdi/New Age), 444 Hz (modern orchestras), 415 Hz (Baroque), or any custom reference.
MIDI note numbers – Get the integer MIDI number for every pitch, useful for DAWs and synth programming.
Acoustic wavelength – Wavelength in air at 20°C (343 m/s), automatically formatted in meters, centimeters, or millimeters.
Octave reference chart – All twelve notes in the chosen octave with frequency, MIDI, and wavelength side by side.

 FAQ

How is musical note frequency calculated?

Under twelve-tone equal temperament, the frequency of any note is f = ref × 2^((n - 69) / 12), where n is the MIDI note number and ref is the reference pitch for A4 (usually 440 Hz). Each semitone multiplies the frequency by the twelfth root of 2 (about 1.05946), and each octave doubles it.
Why are A4 = 440 Hz, 432 Hz, and 444 Hz all used?

440 Hz was standardized by the ISO in 1955 and is the default for almost all modern instruments and recordings. 432 Hz is associated with Verdi and is popular in some classical and meditative-music circles. 444 Hz is used by some modern symphony orchestras for a brighter sound, and 415 Hz (a semitone below 440) is the conventional pitch for Baroque historical performance.
What is a MIDI note number?

MIDI represents pitches as integers from 0 to 127, where 60 is middle C (C4) and 69 is A4. Each semitone increments the number by one, so the same MIDI number always represents the same note name regardless of which reference tuning you pick — only the underlying frequency changes.
What is the difference between equal temperament and just intonation?

Equal temperament splits the octave into twelve mathematically identical semitones, so all keys sound the same but most intervals are slightly out of tune from pure ratios. Just intonation tunes intervals to small integer frequency ratios (3:2 for a perfect fifth, 5:4 for a major third) so they sound perfectly consonant, but it only works in one key at a time.
What is a cent in music?

A cent is a logarithmic unit equal to one-hundredth of an equal-tempered semitone, so an octave is 1200 cents wide. Cents are used to describe small pitch deviations — anything within about ±5 cents is generally indistinguishable from the in-tune note for most listeners, and intonation in trained instrumental playing typically falls within ±10 cents.