Music / Pitch
Note to Frequency Converter and Chart (A4 = 440 Hz or Any Tuning)
Convert a note name to its frequency in hertz, or a frequency to the nearest note and how many cents off it is, with A4 set to 440, 432, 442, or any pitch, the wavelength and period, a play button, and a chart of every note from C0 to B8.
Note to Frequency Converter and Chart (A4 = 440 Hz or Any Tuning): In equal temperament each semitone multiplies the frequency by the 12th root of 2, so f = A4 × 2^((n − 69) ÷ 12), where n is the MIDI note number. Middle C, C4, is 261.63 Hz with A4 at 440; 1,000 Hz is B5 plus 21 cents. The chart recalculates every note for the tuning you choose. Runs 100% locally in your browser with zero server file uploads.
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| Octave | C | C♯ | D | D♯ | E | F | F♯ | G | G♯ | A | A♯ | B |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 | 16.35 | 17.32 | 18.35 | 19.45 | 20.6 | 21.83 | 23.12 | 24.5 | 25.96 | 27.5 | 29.14 | 30.87 |
| 1 | 32.7 | 34.65 | 36.71 | 38.89 | 41.2 | 43.65 | 46.25 | 49 | 51.91 | 55 | 58.27 | 61.74 |
| 2 | 65.41 | 69.3 | 73.42 | 77.78 | 82.41 | 87.31 | 92.5 | 98 | 103.83 | 110 | 116.54 | 123.47 |
| 3 | 130.8 | 138.6 | 146.8 | 155.6 | 164.8 | 174.6 | 185 | 196 | 207.7 | 220 | 233.1 | 246.9 |
| 4 | 261.6 | 277.2 | 293.7 | 311.1 | 329.6 | 349.2 | 370 | 392 | 415.3 | 440 | 466.2 | 493.9 |
| 5 | 523.3 | 554.4 | 587.3 | 622.3 | 659.3 | 698.5 | 740 | 784 | 830.6 | 880 | 932.3 | 987.8 |
| 6 | 1,046.5 | 1,108.7 | 1,174.7 | 1,244.5 | 1,318.5 | 1,396.9 | 1,480 | 1,568 | 1,661.2 | 1,760 | 1,864.7 | 1,975.5 |
| 7 | 2,093 | 2,217.5 | 2,349.3 | 2,489 | 2,637 | 2,793.8 | 2,960 | 3,136 | 3,322.4 | 3,520 | 3,729.3 | 3,951.1 |
| 8 | 4,186 | 4,434.9 | 4,698.6 | 4,978 | 5,274 | 5,587.7 | 5,919.9 | 6,271.9 | 6,644.9 | 7,040 | 7,458.6 | 7,902.1 |
Equal temperament divides the octave into 12 equal semitones, each a factor of the 12th root of 2, about 1.0595: f = A4 × 2^((n − 69) ÷ 12), where n is the MIDI note number. Concert pitch is A4 = 440 Hz; some orchestras tune to 442 or 443, Baroque ensembles to 415. Middle C is C4, 261.63 Hz.
Octaves
Each octave doubles the frequency: A3 is 220 Hz, A4 440 Hz, and A5 880 Hz. A piano's 88 keys run from A0 at 27.5 Hz to C8 at 4,186 Hz.
Hearing a pitch
To play a sustained tone at any frequency, or sweep across a range, use the tone generator.
How to use it
- Type a note, such as A4 or B♭3, or a frequency in Hz.
- Set the A4 tuning if it is not 440 Hz.
- Read the frequency or the nearest note, and play it.
Privacy & limitations
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Related tools
Frequently asked questions
Why is A4 440 Hz?
It became the international standard pitch in 1939 and was confirmed as ISO 16 in 1975, though many orchestras tune slightly higher, to 442 or 443.
What is a cent?
A hundredth of a semitone; differences of a few cents are hard to hear, while 20 or more sound clearly out of tune.
Is 432 Hz tuning special?
It is simply A4 about 32 cents lower than 440; claims about special effects on the body are not supported by evidence.
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