Tuning & Temperament
What Are Cents? The Unit That Measures Small Pitch Differences
A cent is one hundredth of an equal-tempered semitone. Here is the formula, what the common intervals measure in cents, and what a tuner is showing you.
Cent
A unit for small pitch differences: 1/100 of an equal-tempered semitone, so an octave is 1200 cents.
Also called: cents, cents of pitch
A cent is 1/100 of an equal-tempered semitone, so an octave of twelve equal semitones contains 1200 cents. The unit is logarithmic. The number of cents between two frequencies is 1200 times the base-2 logarithm of their ratio. An equal semitone is 100 cents, and the equal-tempered fifth is 700 cents. A perfect fifth in just intonation, at 3:2, is about 701.96 cents, so it is 1.96 cents wider than the equal fifth. A tuner typically shows deviation in cents, and differences of a few cents are audible when two tones sound together. The cent gives tuning a precise scale without a separate unit for each interval.
Related terms
- Equal temperamentA tuning that divides the octave into twelve equal semitones of 100 cents, so every key sounds alike and no interval is pure.
- Just intonationA tuning built from simple whole-number frequency ratios, so intervals ring clean but the sizes of steps vary by key.
- Pythagorean commaThe gap of about 23.46 cents left when twelve pure fifths are stacked and compared with seven octaves.