Scientific pitch notation creates a linear pitch space in which an octave spans 12 semitones, where each semitone is the distance between adjacent keys of the piano keyboard. Distance in this space corresponds to musical pitch distance in an equal-tempered scale; 2 semitones being a whole step, 1 semitone being a half step. An equal-tempered semitone can also be subdivided further into 100 cents. Each cent is semitone or octave. This measure of pitch allows the expression of "microtones" not found on standard piano keyboards. The notation is sometimes used in the context of meantone temperament, and does not always assume equal temperament
Augmented seventh plus the difference between the chromatic and diatonic semitones, which makes it a highly variable quantity between one meantone tuning and the next. In standard equal temperament, in fact, it is identical to the perfect octave (), because both semitones have the same size. In 19 equal temperament, on the other hand, the interval is 63 cents short of an octave, i.e. 1137 cents. More typical meantone tunings fall between these extremes, giving it an intermediate size. In just intonation, three major thirds in succession make up an augmented seventh, which is just short of an octave by 41.05 cents.