Music Intervals
An interval is the distance in pitch between two notes, measured in semitones (half steps). Its name combines a number — like a third or a fifth — with a quality such as perfect, major, or minor.
Interval chart
Every interval within one octave: how many semitones it spans, its quality, an example built up from C, and a well-known melody that opens with that leap.
| Interval | Semitones | Quality | Example (from C) | Song mnemonic |
|---|---|---|---|---|
| Perfect unison | 0 | Perfect | C–C | — |
| Minor 2nd | 1 | Minor | C–D♭ | "Jaws" |
| Major 2nd | 2 | Major | C–D | "Happy Birthday" |
| Minor 3rd | 3 | Minor | C–E♭ | "Greensleeves" |
| Major 3rd | 4 | Major | C–E | "When the Saints" |
| Perfect 4th | 5 | Perfect | C–F | "Here Comes the Bride" |
| Tritone (Aug 4th) | 6 | Augmented | C–F♯ | "The Simpsons" / "Maria" |
| Perfect 5th | 7 | Perfect | C–G | "Twinkle Twinkle" |
| Minor 6th | 8 | Minor | C–A♭ | — |
| Major 6th | 9 | Major | C–A | "My Bonnie" |
| Minor 7th | 10 | Minor | C–B♭ | "Star Trek" theme |
| Major 7th | 11 | Major | C–B | — |
| Perfect octave | 12 | Perfect | C–C | "Somewhere Over the Rainbow" |
Understanding intervals
The smallest step in Western music is the semitone, or half step — the distance between two adjacent keys on a piano, black or white. Two semitones make a whole tone, or whole step. Every interval on the chart above is just a count of semitones: a major third is four, a perfect fifth is seven, and a full octave is twelve. Counting half steps is the most reliable way to identify or build any interval by ear or on paper.
Number and quality
An interval's number — second, third, fourth, and so on — comes from how many letter names it covers. Its quality refines the exact size. The unison, fourth, fifth, and octave take the label perfect, because they are the most stable and were treated as consonances first in Western harmony. The second, third, sixth, and seventh come in major and minor forms one semitone apart. Widen a perfect or major interval by a semitone and it becomes augmented; narrow a perfect or minor interval by a semitone and it becomes diminished — which is why the six-semitone tritone can be spelled as an augmented fourth or a diminished fifth.
Consonance and dissonance
Perfect unisons, octaves, and fifths sound the most stable and consonant; major and minor thirds and sixths are gently consonant and are the building blocks of triads. Seconds, sevenths, and the tritone are dissonant — they create tension that wants to resolve, which is exactly what makes them useful for driving music forward.
Inversions
Flip an interval by moving the lower note up an octave and you get its inversion. A perfect fifth inverts to a perfect fourth, a major third to a minor sixth, a major second to a minor seventh. The two interval numbers always add up to nine (a fifth plus a fourth), and their semitone counts add up to twelve. To hear intervals cleanly in tune, sound each note against the chromatic tuner, and see how fifths chain together on the circle of fifths.
Frequently asked questions
What is a musical interval?
A musical interval is the distance in pitch between two notes, measured in semitones (half steps). Every interval is named by a number that gives its size on the staff, like a third or a fifth, and a quality such as perfect, major, minor, augmented, or diminished.
How many semitones are in a perfect fifth?
A perfect fifth spans seven semitones — for example, C up to G. It is one of the most consonant intervals in music and is the step that generates the circle of fifths.
What is a tritone?
A tritone is the interval of six semitones, exactly half of an octave — for example, C to F♯. It is also called an augmented fourth or diminished fifth, and its tense, dissonant sound gives dominant seventh chords their pull toward resolution.
What is the difference between a major and minor third?
A major third is four semitones (C to E) and a minor third is three semitones (C to E flat). The major third sounds bright and forms the bottom of a major chord, while the minor third sounds darker and forms the bottom of a minor chord.
Hear every interval in tune.
Sound two notes and check the pitch of each with the free online chromatic tuner.