A unit of measure of the width of a

musical interval, equal to 1/100 of a

*semitone*,

**not** a

whole tone. You can find the number of cents in a

just intonation interval from the

frequency ratio by this formula:

cents = log(ratio) / log(2) * 1200

Thus the octave, ratio 2/1, measures 1200 cents, which makes sense because it is equal to twelve equal tempered semitones each 100 cents.