Note frequency

What frequency is a musical note?

Convert a note to hertz or a frequency to its nearest note, with cents, MIDI number, an octave table and the sound of it.

Pitch

Convert

Note

Octave

Reference pitch

A4 reference

The standard is 440 Hz; orchestras often tune a little higher.

Octave and names

Table

Notes of octave 4 with their frequencies

Notes of octave 4 with their frequencies
Note	MIDI	Hz
C4	60	261.63
C♯4	61	277.18
D4	62	293.66
D♯4	63	311.13
E4	64	329.63
F4	65	349.23
F♯4	66	369.99
G4	67	392
G♯4	68	415.3
A4	69	440
A♯4	70	466.16
B4	71	493.88

Interval between two frequencies

From

The interval

Cents: +701.96
Semitones: +7.02
Ratio: 1.5

Frequency

440 Hz

A4, MIDI note 69

How to use

Choose Note to frequency, then pick the note and its octave; or choose Frequency to note and type a frequency.
Read the frequency or the nearest note and how many cents sharp or flat it is.
Change the A4 reference if your instrument or ensemble tunes to something other than 440 Hz.
Press Play the note to hear it, or play any key of the keyboard.

How it works

Western music divides each octave into twelve equal steps, called semitones. Going up one octave doubles the frequency, so every semitone multiplies it by the same amount, about 1.0595. Notes are pinned to one reference: the A above middle C (A4), normally 440 Hz.

The frequency of a note with MIDI number m is f = A4 × 2^((m − 69) / 12), where A4 is the reference frequency and 69 is the MIDI number of A4. For example, middle C is MIDI 60, so f = 440 × 2^(−9/12) ≈ 261.63 Hz. The distance between two frequencies is measured in cents, 1200 × log₂(f₂ / f₁): one semitone is 100 cents, an octave 1200.

This is equal temperament, which is what pianos and most modern instruments use. Other tunings, such as just intonation, place the notes a few cents differently. Octave numbers follow scientific pitch notation, so middle C is C4. In the German and Nordic system the note B is called H and B flat is called B.

Frequently asked questions

What frequency is middle C?

About 261.63 Hz when A4 is 440 Hz. It is C4, MIDI note 60.

Why is the note called H in German and Finnish?

In the German system the plain B is written H, and B flat is written B. English and most other languages call them B and B flat.

What are cents?

Cents are hundredths of a semitone. A difference under about 5 cents is hard to hear for most people, while 50 cents is exactly halfway between two notes.

Why change the A4 reference?

Some orchestras tune to 442 Hz or higher for a brighter sound, and baroque ensembles often tune to 415 Hz, about a semitone lower.

Does this support just intonation?

No. The frequencies use twelve-tone equal temperament. Other tuning systems can give different frequencies for the same note names.