What frequency is middle C, and which note is hiding in 1000 Hz? The calculator converts note names, MIDI numbers and frequencies into each other in any direction: whatever you typed last decides. If a frequency falls between two notes, it names the nearest one and the offset in cents. Concert pitch can be set between 400 and 480 Hz, for example to 443 Hz as some orchestras tune.
What frequency is a note, and what note is hiding in a frequency? Useful for tuning oscillators and setting filters.
In the generator Oscillator: frequency, detune · Filter: cutoff
Spelling: C4 is middle C, accidentals as F#3 or Eb5; B is B natural, which German notation calls H. The formula: note name = MIDI mod 12, frequency = reference · 2^((MIDI − 69) / 12).
In equal temperament every octave is split into twelve equal semitone steps. One octave up doubles the frequency, one semitone up multiplies it by 21/12 ≈ 1.0595. Counting starts at concert pitch A4 = 440 Hz, MIDI number 69:
Example: C4, middle C, has MIDI number 60 and lies nine semitones below A4: 440 Hz · 2−9/12 = 261.63 Hz. The other way round, 1000 Hz gives MIDI number 83.21, which is B5 plus 21 cents.
Notation: C4 is middle C. Accidentals are written as F#3 or Eb5. In German, B is called H and B♭ is called B.
| Note / octave | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
|---|---|---|---|---|---|---|---|---|---|
| C | 16.35 | 32.70 | 65.41 | 130.81 | 261.63 | 523.25 | 1,046.50 | 2,093.00 | 4,186.01 |
| C♯/D♭ | 17.32 | 34.65 | 69.30 | 138.59 | 277.18 | 554.37 | 1,108.73 | 2,217.46 | 4,434.92 |
| D | 18.35 | 36.71 | 73.42 | 146.83 | 293.66 | 587.33 | 1,174.66 | 2,349.32 | 4,698.64 |
| D♯/E♭ | 19.45 | 38.89 | 77.78 | 155.56 | 311.13 | 622.25 | 1,244.51 | 2,489.02 | 4,978.03 |
| E | 20.60 | 41.20 | 82.41 | 164.81 | 329.63 | 659.26 | 1,318.51 | 2,637.02 | 5,274.04 |
| F | 21.83 | 43.65 | 87.31 | 174.61 | 349.23 | 698.46 | 1,396.91 | 2,793.83 | 5,587.65 |
| F♯/G♭ | 23.12 | 46.25 | 92.50 | 185.00 | 369.99 | 739.99 | 1,479.98 | 2,959.96 | 5,919.91 |
| G | 24.50 | 49.00 | 98.00 | 196.00 | 392.00 | 783.99 | 1,567.98 | 3,135.96 | 6,271.93 |
| G♯/A♭ | 25.96 | 51.91 | 103.83 | 207.65 | 415.30 | 830.61 | 1,661.22 | 3,322.44 | 6,644.88 |
| A | 27.50 | 55.00 | 110.00 | 220.00 | 440.00 | 880.00 | 1,760.00 | 3,520.00 | 7,040.00 |
| A♯/B♭ | 29.14 | 58.27 | 116.54 | 233.08 | 466.16 | 932.33 | 1,864.66 | 3,729.31 | 7,458.62 |
| B | 30.87 | 61.74 | 123.47 | 246.94 | 493.88 | 987.77 | 1,975.53 | 3,951.07 | 7,902.13 |
Frequencies in Hz at A4 = 440 Hz, rounded to two decimal places. Highlighted: middle C (C4) and concert pitch A4. MIDI number = 12 · (octave + 1) + note, with C = 0 to B = 11.
ModuloOne is a modular synthesizer that runs in your browser: connect modules with cables and hear what comes out. There the oscillator sets the frequency (20 to 2,000 Hz), and fine tuning moves it by −50 to 50 cents; when a sequencer plays the melody, it sets the notes. The cutoff of a filter is a frequency too (20 to 12,000 Hz). Open the generator