 Frequency difference

 
This calc gives the frequency of a note that is a given musical interval away from a given note (assigned by frequency). This is done by a simple exponential relationship, assuming that there are 12 semitones for each doubling of frequency. The ratio of frequencies of the old and news notes is also given.
 
Note that this calc uses equal temperament (i.e. it assumes that an octave divides exactly into 12 semitones). This is the way that the majority of modern music is played. For this reason, there may be some small differences to expectation e.g. an interval of 7 semitones (perfect 5th) does not give an exact 2:3 ration of frequencies.  