Semitone Calculator
Select a starting note and shift by any number of semitones to see the resulting frequency, interval name, and frequency ratio. This calculator uses equal temperament tuning and lets you adjust the A4 reference pitch for historical or alternative tuning systems.
In equal temperament (the standard tuning system), each semitone raises the pitch by a factor of 2^(1/12), which is approximately 1.05946. Twelve semitones make one octave, which doubles the frequency.
Common intervals and their semitone counts:
- Minor 3rd: 3 semitones (ratio 1.189)
- Major 3rd: 4 semitones (ratio 1.260)
- Perfect 4th: 5 semitones (ratio 1.335)
- Perfect 5th: 7 semitones (ratio 1.498)
- Octave: 12 semitones (ratio 2.000)
Cents are a finer subdivision. One semitone = 100 cents. Cents are useful for measuring tiny pitch differences, like the 2-cent detuning between equal temperament and just intonation thirds.