How this calculator works
An interval is the distance between two notes, counted in semitones and named by the written distance. Counting only the semitones gives the size in steps, and the two names line up once you know the pattern: a minor second is one semitone, a major second is two, a minor third is three, and so on through the octave. Between notes without octaves this page treats the second note as the higher one within the same octave, so C to G is a perfect fifth and G to C is a perfect fourth. With octaves included, the result can be a compound interval, such as a major tenth for C4 up to E5.
Formula
semitones = second note number - first note number, where note numbers run chromatically by semitone. The interval name comes from the absolute semitone count: 0 unison, 1 minor second, 2 major second, 3 minor third, 4 major third, 5 perfect fourth, 6 tritone, 7 perfect fifth, 8 minor sixth, 9 major sixth, 10 minor seventh, 11 major seventh, 12 octave. Whole tones = semitones / 2.
Worked example
C to G is seven semitones, a perfect fifth and 3.5 whole tones. E to C is eight semitones, a minor sixth. With octaves, C4 to E5 is sixteen semitones: the simple interval is a major third and the octave adds twelve semitones, so the name is a major third plus one octave, commonly called a major tenth, and the direction is up.
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Frequently asked questions
Why is the interval from E to C a minor sixth?
The letter names count six steps (E, F, G, A, B, C), and the semitone count is eight. A major sixth would be nine semitones, as in C to A, so eight is the minor sixth. The written distance decides whether it is a sixth, and the semitone count decides major, minor or perfect.
What is a tritone?
Six semitones, halfway around the octave. It can be written as an augmented fourth, for example F to B, or a diminished fifth, for example B to F. The sound is the same in equal temperament, but the spelling and how the interval resolves differ.
How do compound intervals get their names?
Subtract twelve semitones for each octave and name the remainder, then add the octaves back. A major ninth is a major second plus an octave, a perfect eleventh is a perfect fourth plus an octave, and a major thirteenth is a major sixth plus an octave.
Does direction matter?
For the name, no: an octave up and an octave down are both octaves. For the semitone count this page keeps the sign, so C4 to G5 is positive and G5 to C4 is negative. The direction field says which way the second pitch lies.