Note Frequencies

The octave number is in the left column. To find the frequency of middle C, which is C4, look down the "C" column until you get to the "4" row. Middle C is 261.6 Hz.

Some Specific Notes

Middle C: C4=261.6Hz

Standard tuning fork A: A4=440Hz

Piano range: A0=27.50Hz to C8=4186Hz

Guitar strings: E2=82.41Hz, A2=110Hz, D3=146.8Hz, G3=196Hz, B3=246.9Hz, E4=329.6Hz

Bass strings: (5th string) B0=30.87Hz, (4th string) E1=41.20Hz, A1=55Hz, D2=73.42Hz, G2=98Hz

Mandolin & violin strings: G3=196Hz, D4=293.7Hz, A4=440Hz, E5=659.3Hz

Viola & tenor banjo strings: C3=130.8Hz, G3=196Hz, D4=293.7Hz, A4=440Hz

Cello strings: C2=65.41Hz, G2=98Hz, D3=146.8Hz, A3=220Hz

Closing Thoughts

Keep in mind that everything here is in relation to the even-tempered or equally-tempered scale, where an octave is a frequency ratio of exactly two and a semitone is a frequency ratio of exactly the twelfth root of two. In the real world, however, many different temperaments may be used - see en.wikipedia.org/wiki/Musical_temperament - and octaves too can vary in size, see en.wikipedia.org/wiki/Stretched_octave.

I call middle C "C4." This is the most octave numbering but some people call middle C "C3" or even "C5."