MAIN INTERVAL NAMES :
( The intervals within one octave )
P1 : ( perfect unison ) = 0 semitones
d2 : ( diminshed second ) = 0 semitones
m2 : ( minor second ) = 1 semitone
A1 : ( augmented unison ) = 1 semitone
M2 : ( Major second ) = 2 semitones
d3 : ( diminished third ) = 2 semitones
m3 : ( minor third ) = 3 semitones
A2 : ( augmented second ) = 3 semitones
M3 : ( Major third ) = 4 semitones
d4 : ( diminished fourth ) = 4 semitones
P4 : ( perfect fourth ) = 5 semitones
A3 : ( augmented third ) = 5 semitones
aug4 : ( augmented fourth ) = 6 semitones
dim5 : ( diminished fifth ) = 6 semitones
P5 : ( perfect fifth ) = 7 semitones
d6 : ( diminished sixth ) = 7 semitones
m6 : ( minor sixth ) = 8 semitones
A5 : ( augmented fifth ) = 8 semitones
M6 : ( Major sixth ) = 9 semitones
dim7 : ( diminished seventh ) = 9 semitones
m7 : ( minor seventh ) = 10 semitones
A6 : ( augmented sixth ) = 10 semitones
M7 : ( Major seventh ) = 11 semitones
d8 : ( diminished octave ) = 11 semitones
P8 : ( perfect octave ) = 12 semitones
A7 : ( augmented seventh ) = 12 semitones
COMPOUND INTERVAL NAMES :
( names of intervals which span more than one octave )
d9 : ( diminished ninth ) = 12 semitones
m9 : ( minor ninth ) = 13 semitones
A8 : ( augmented octave ) = 13 semitones
M9 : ( Major ninth ) = 14 semitones
d10 : ( diminished tenth ) = 14 semitones
m10 : ( minor tenth ) = 15 semitones
A9 : ( augmented ninth ) = 15 semitones
M10 : ( Major tenth ) = 16 semitones
d11 : ( diminished eleventh ) = 16 semitones
P11 : ( perfect eleventh ) = 17 semitones
A10 : ( augmented tenth ) = 17 semitones
d12 : ( diminished twelfth ) = 18 semitones
A11 : ( augmented eleventh ) = 18 semitones
P12 : ( perfect twelfth, tritave ) = 19 semitones
d13 : ( diminished 13th ) = 19 semitones
m13 : ( minor thirteenth ) = 20 semitones
A12 : ( augmented twelfth ) = 20 semitones
M13 : ( major thirteenth ) = 21 semitones
d14 : ( diminished fourteenth ) = 21 semitones
m14 : ( minor fourteenth ) = 22 semitones
A13 : ( augmented thirteenth ) = 22 semitones
M14 : ( Major fourteenth ) = 23 semitones
d15 : ( diminished fifteenth ) = 23 semitones
P15 : ( perfect fifteenth, double octave ) = 24 semitones
A14 : ( augmented fourteenth ) = 24 semitones
A15 : ( augmented fifteenth ) = 25 semitones
M17 : ( major seventeenth ) = 28 semitones
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Melodic intervals occur sequentially.
Harmonic intervals occur simultaneously.
Compound intervals are intervals that span more than one octave.
Simple intervals are equal to or less than one octave in distance.
An augmented fourth ( or diminished fifth ) is called a tritone because it encompasses three whole steps.
C up to G is a ‘fifth’ because it encompasses five letter names ( C D E F G ).
C down to G is a fourth because it encompasses four letter names ( C B A G ).
Interval inversions : When the top member of an interval is moved to the octave below the bottom member ( or vice versa ), the interval is said to be inverted.
A major interval contracted or decreased by a half step ( semitone ) is called minor.
A major or perfect interval expanded or increased by a half step ( semitone ) is called augmented.
A minor or perfect ineterval contracted or decreased by a half step ( semitone ) is called diminished.