Equal-Temperament Note Frequency

In equal temperament, the octave is divided into 12 equal frequency ratios, so each semitone multiplies pitch by the same constant factor instead of adding a fixed number of hertz. Because 12 semitones make one octave and an octave means doubling the frequency, the per-semitone factor must be 2^(1/12), which gives the formula f_n = f_0 × 2^(n/12). Positive n raises the pitch above the reference note, negative n lowers it, and n = 12 gives exactly twice the frequency.

Use this when you need to find the frequency of a musical note relative to a known reference pitch in standard tuning, such as converting note names to Hz or comparing intervals. It is especially useful in acoustics, instrument tuning, digital audio, and music theory calculations.

• Using n as the number of whole octaves instead of semitones
• Adding 2/12 to the frequency instead of multiplying by 2^(n/12)
• Forgetting that negative n means the note is below the reference pitch