The 12-Tone Equal Temperament (12-TET) formula is used to calculate the frequency of any note relative to a reference pitch in an equally divided octave system. In 12-TET, an octave is divided into 12 logarithmically equal steps, meaning each semitone increases in frequency by a factor of 2^{1/12}. The formula for determining the frequency f_n of a note n semitones away from a reference frequency f_0 is:
f_n = f_0 \times 2^{(n/12)}