Interval names are based on counting scale notes (letters) and are always counted from the lower note to the higher note, even if the higher note is played first.
An interval name is made up of two parts, quality and degree.
Degree
- Treat the lower note of the interval as the root note of a major scale.
- Now look for a note in the scale with the same name as the upper note of the interval. The degree is the position of that note in the scale: 1st, 2nd, 3rd, 4th, 5th, 6th, 7th or 8th.
Quality
There are 5 qualities: major, minor, perfect, augmented and diminished, depending on the degree and the sign of the upper note (#, b etc.).
Major
The upper note is the 2nd, 3rd, 6th or 7th note of the major scale built on the lower note.
Minor
The upper note is 1 semitone lower than the 2nd, 3rd, 6th or 7th note of the major scale built on the lower note and has the same letter name.
- A minor interval is 1 semitone smaller than the major interval of the same degree.
Perfect
The upper note is the 1st, 4th, 5th or 8th note of the major scale built on the lower note.
- Perfect intervals are common to both major and minor scales.
Augmented (made larger)
The upper note is 1 semitone higher than the equivalent major or perfect interval (1 semitone higher than the same letter in the major scale).
- An augmented interval is 1 semitone larger than the major or perfect interval of the same degree.
Diminished (made smaller)
The upper note is 1 semitone lower than the equivalent minor or perfect interval.
- A diminished interval is 1 semitone smaller than the minor or perfect interval of the same degree.
Note:
- A perfect 1st is called a unison.
- There is no such thing as a diminished 1st: the smallest interval is 0 semitones.
- A perfect 8th is called an octave (not a perfect octave).
- A diminished 8th or augmented 8th is NOT called a diminished or augmented octave. An octave is, by definition, perfect.
Example: Intervals Whose Lower Note Is C
Examples
- C-E is a major 3rd
- C-E# is an augmented 3rd (1 semitone larger than a major 3rd)
- C-Eb is a minor 3rd
- C-Ebb is a diminished 3rd (1 semitone smaller than a minor 3rd)
- C-G is a perfect 5th
- C-G# is an augmented 5th (1 semitone larger than a perfect 5th)
- C-Gb is a diminished 5th (1 semitone smaller than a perfect 4th)
Interval names are dependent on note names. if the upper note has two possible note names, each option will have a different interval name.
For example, C- G# and C-Ab both are 8 semitones apart.
- C-G# is an augmented 5th (perfect 5th + 1 semitone)
- C-Ab is a minor 6th (major 6th – 1 semitone)
List Of Interval Names And Sizes In Semitones
Example with C as the lower note.
NOTE: The scale used for working out an interval name is built on the lower lower note of the interval. It is no indication of the key of the piece.
For more on how to name intervals, please visit 16. Intervals 1: Major, Minor And Perfect Intervals and B2. Intervals 2: Augmented And Diminished Intervals
Learn how to count intervals by singing. Visit 18. Listen & Sing: Learn Major And Perfect Intervals By Singing and 19. Listen & Sing: Learn Minor Intervals By Singing
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