A musical interval is the distance between two pitches, measured in semitones and named by number (second, third, fifth, etc.) and quality (major, minor, perfect, augmented, diminished).
A musical interval is the distance in pitch between two notes. Intervals are the building blocks of scales, chords, melodies, and harmonic progressions — understanding intervals is foundational to music theory.
Intervals are measured by two properties: number and quality.
The number describes how many staff positions (letter names) apart the two notes are, counting the bottom note as 1. From C to D is a second; C to E is a third; C to G is a fifth; C to C (the octave) is an eighth (octave).
The quality — major, minor, perfect, augmented, or diminished — describes the exact number of semitones. A major third (C to E) spans 4 semitones. A minor third (C to Eb) spans 3 semitones. A perfect fifth (C to G) spans 7 semitones. The difference between major and minor is always one semitone.
Perfect intervals (unison, fourth, fifth, octave) are called 'perfect' because they are particularly consonant and stable, and they do not have major/minor variants — only perfect, augmented, or diminished.
Ear training for intervals: each interval has a characteristic sound learnable by association with a familiar song. A major second = Happy Birthday (first two notes). A major third = When the Saints Go Marching In. A perfect fourth = Here Comes the Bride. A perfect fifth = Star Wars theme. A major sixth = My Bonnie Lies Over the Ocean. A major seventh = Take On Me (first two notes). An octave = Somewhere Over the Rainbow.
Inverted intervals: when the lower note moves up an octave (or the upper note moves down), the interval is inverted. The numbers of an interval and its inversion add up to 9. The quality changes: major becomes minor, and vice versa; perfect stays perfect.
Music theory teachers on Virgoul build interval recognition into lessons from the start — developing your ear alongside your technical skills so you understand what you are hearing, not just what you are playing.
Join VirgoulThe 12 intervals within one octave (by semitone count): minor 2nd (1), major 2nd (2), minor 3rd (3), major 3rd (4), perfect 4th (5), tritone/augmented 4th/diminished 5th (6), perfect 5th (7), minor 6th (8), major 6th (9), minor 7th (10), major 7th (11), octave (12). Each has a distinct sound character learnable through ear training.
A major interval is one semitone larger than the equivalent minor interval. A major third spans 4 semitones; a minor third spans 3. A major sixth spans 9 semitones; a minor sixth spans 8. The quality (major vs. minor) is determined by counting the exact semitones between the two notes. Major intervals generally sound brighter and more stable; minor intervals sound darker or more tense.
Perfect intervals are the unison (0 semitones), perfect fourth (5 semitones), perfect fifth (7 semitones), and octave (12 semitones). They are called 'perfect' because they are particularly consonant and stable — their overtone relationships are especially simple. Unlike seconds, thirds, sixths, and sevenths, perfect intervals do not have major and minor versions; instead they are perfect, augmented (one semitone larger), or diminished (one semitone smaller).
The tritone is the interval of exactly 6 semitones — the augmented fourth or diminished fifth. It divides the octave exactly in half and is the most dissonant interval in Western music. In medieval music theory it was called 'diabolus in musica' (the devil in music) and its use was restricted. In tonal harmony, the tritone creates strong tension that wants to resolve — the dominant seventh chord contains a tritone between its third and seventh, which is why V7 chords resolve so powerfully to the tonic.
Associate each interval with the opening notes of a familiar song: minor 2nd = Jaws theme; major 2nd = Happy Birthday; minor 3rd = Smoke on the Water riff; major 3rd = When the Saints Go Marching In; perfect 4th = Here Comes the Bride; tritone = The Simpsons theme; perfect 5th = Star Wars; minor 6th = The Entertainer; major 6th = My Bonnie; minor 7th = Somewhere (West Side Story); major 7th = Take On Me; octave = Somewhere Over the Rainbow. Practice with ear training apps until recognition becomes automatic.