tuning

TUNING

VIOLIN strings: G3=196Hz, D4=293.7Hz, A4=440Hz, E5=659.3Hz
VIOLA strings: C3=130.8Hz, G3=196Hz, D4=293.7Hz, A4=440Hz
CELLO strings: C2=65.41Hz, G2=98Hz, D3=146.8Hz, A3=220Hz

Standard tuning fork / pitch pipe: A4=440Hz (440 cicles per second, or “440cps”)
Middle C: C4=261.6Hz
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

Following is a table giving the frequencies of musical pitches in Hertz (Hz) values, covering the full range of common musical instruments. It uses as reference an even tempered scale where
A = 440Hz.

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

Tuning pitches (click to play)

VIOLIN A D G E
VIOLA A D G C
CELLO A D G C

Further references:
Musical Tuning
Temperament