A musical octave spans a factor of two in frequency and there are twelve
notes per octave. Notes are separated by the factor 2 ^{1/12 }or
1.059463. (1.059463 x 1.059463 x 1.059463...continued for a total of twelve = 2;
try it!)

Notes |
Frequency (octaves) |
||||

A |
55.00 |
110.00 |
220.00 |
440.00 |
880.00 |

A# |
58.27 |
116.54 |
233.08 |
466.16 |
932.32 |

B |
61.74 |
123.48 |
246.96 |
493.92 |
987.84 |

C |
65.41 |
130.82 |
261.64 |
523.28 |
1046.56 |

C# |
69.30 |
138.60 |
277.20 |
554.40 |
1108.80 |

D |
73.42 |
146.84 |
293.68 |
587.36 |
1174.72 |

D# |
77.78 |
155.56 |
311.12 |
622.24 |
1244.48 |

E |
82.41 |
164.82 |
329.64 |
659.28 |
1318.56 |

F |
87.31 |
174.62 |
349.24 |
698.48 |
1396.96 |

F# |
92.50 |
185.00 |
370.00 |
740.00 |
1480.00 |

G |
98.00 |
196.00 |
392.00 |
784.00 |
1568.00 |

A♭ |
103.83 |
207.66 |
415.32 |
830.64 |
1661.28 |

Starting at any note the frequency to other notes may be calculated from its frequency by:

Freq = note x 2 ^{N/12},

where N is the number of notes away from the starting note. N may be positive, negative or zero.

For example, starting at D (146.84 Hz), the frequency to the next higher F is:

146.84 x 2 ^{3/12} = 174.62,

since F is three notes above. The frequency of A in the next lower octave is:

146.84 x 2 ^{-17/12} = 55,

since there are 17 notes from D down to the lower A.

The equation will work starting at any frequency but remember that the N value for the starting frequency is zero.