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Note Frequency Calculator
Convert musical notes to frequencies and back. Enter a note and octave to get its exact pitch in Hz, or enter a frequency to find the nearest note, how many cents sharp or flat it is and its MIDI number. Change the A4 reference for 432, 442 or baroque tuning.
Convert
Middle C is C4 (scientific pitch notation).
¢
Hz
Hz
440 Hz is the modern standard; some orchestras use 442, baroque 415.
Enter your values to see the result.
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How to use the Note Frequency Calculator
- Choose the direction: note to frequency, or frequency to note.
- Pick the note and octave (middle C is C4), or enter a frequency in Hz.
- Change the A4 reference if you tune to something other than 440 Hz.
- Read the frequency or nearest note, cents offset and MIDI number.
- Scroll the table for every note from C0 to B8, and download it as CSV.
Note frequency formula
Modern Western music uses twelve-tone equal temperament: the octave is split into 12 equal semitones, and each one multiplies the frequency by 21/12 ≈ 1.059463.
f = A4 × 2(m − 69) ÷ 12 and m = 69 + 12 × log₂(f ÷ A4)
Here m is the MIDI note number (C4 = 60, A4 = 69) and A4 is the reference pitch, normally 440 Hz. The MIDI number of a note is (octave + 1) × 12 + its position in the octave (C = 0, C♯ = 1 … B = 11).
Example: E2, the low guitar string, has m = (2 + 1) × 12 + 4 = 40, so f = 440 × 2(40 − 69) ÷ 12 = 82.41 Hz.
Note frequency chart (A4 = 440 Hz)
| Note | Octave 1 | 2 | 3 | 4 | 5 | 6 | 7 |
|---|---|---|---|---|---|---|---|
| C | 32.70 | 65.41 | 130.81 | 261.63 | 523.25 | 1046.50 | 2093.00 |
| C♯ | 34.65 | 69.30 | 138.59 | 277.18 | 554.37 | 1108.73 | 2217.46 |
| D | 36.71 | 73.42 | 146.83 | 293.66 | 587.33 | 1174.66 | 2349.32 |
| D♯ | 38.89 | 77.78 | 155.56 | 311.13 | 622.25 | 1244.51 | 2489.02 |
| E | 41.20 | 82.41 | 164.81 | 329.63 | 659.26 | 1318.51 | 2637.02 |
| F | 43.65 | 87.31 | 174.61 | 349.23 | 698.46 | 1396.91 | 2793.83 |
| F♯ | 46.25 | 92.50 | 185.00 | 369.99 | 739.99 | 1479.98 | 2959.96 |
| G | 49.00 | 98.00 | 196.00 | 392.00 | 783.99 | 1567.98 | 3135.96 |
| G♯ | 51.91 | 103.83 | 207.65 | 415.30 | 830.61 | 1661.22 | 3322.44 |
| A | 55.00 | 110.00 | 220.00 | 440.00 | 880.00 | 1760.00 | 3520.00 |
| A♯ | 58.27 | 116.54 | 233.08 | 466.16 | 932.33 | 1864.66 | 3729.31 |
| B | 61.74 | 123.47 | 246.94 | 493.88 | 987.77 | 1975.53 | 3951.07 |
Each octave doubles the frequency: A2 = 110 Hz, A3 = 220 Hz, A4 = 440 Hz, A5 = 880 Hz. The 88-key piano runs from A0 (27.5 Hz) to C8 (4186.01 Hz).
Frequently asked questions
How do you calculate the frequency of a note?
In twelve-tone equal temperament every semitone multiplies the frequency by the twelfth root of 2 (about 1.05946). Using MIDI numbers, f = 440 × 2^((m − 69) ÷ 12), where m is the MIDI note number and 69 is A4.
What frequency is middle C?
Middle C (C4, MIDI note 60) is 261.63 Hz when A4 is tuned to 440 Hz. It is 3 semitones above A3 and 9 semitones below A4.
How do I find the note from a frequency?
Compute m = 69 + 12 × log₂(f ÷ 440). The nearest whole number is the MIDI note, and the remainder times 100 is how many cents sharp or flat the frequency is. For example 432 Hz is A4 about 31.8 cents flat.
What is a cent in music?
A cent is one hundredth of an equal-tempered semitone, so an octave has 1200 cents. Most listeners notice pitch differences of around 5 to 10 cents, which is why tuners aim for within a few cents.
What is the frequency of each guitar string?
In standard tuning the open strings are E2 82.41 Hz, A2 110 Hz, D3 146.83 Hz, G3 196 Hz, B3 246.94 Hz and E4 329.63 Hz.
Why is A4 set to 440 Hz?
A4 = 440 Hz was adopted as the international standard concert pitch (ISO 16). Some orchestras tune slightly higher, at 442 or 443 Hz, and baroque ensembles often use 415 Hz. Change the reference field to match your tuning.
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