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Pitch & Intervals

Interval

Definition

An interval is the distance in pitch between two notes. It is named by counting letter names (a 3rd, a 5th) and described by its quality: major, minor, perfect, augmented or diminished.

An interval is the distance between two pitches. When the two notes sound one after the other it is a melodic interval; when they sound together it is a harmonic interval. Melodies are chains of melodic intervals, and chords are stacks of harmonic ones.

Two treble-clef examples. Left: half notes C4 then E4. Right: C4 and E4 together as a whole note.
The same major 3rd, C4–E4, as a melodic interval (one note after the other, left) and as a harmonic interval (both together, right).

Step 1: the number

Count the letter names from the lower note to the upper one, including both. C up to E is C–D–E, three letters, so it is a 3rd. C up to G is a 5th. Two notes on the same pitch form a unison, and eight letters make an octave. On the staff the count is quick: a 3rd goes from a line to the next line (or a space to the next space), a 2nd from a line to the space right above it.

Accidentals don't change the number. C–E, C–E♭ and C♯–E are all 3rds, because the letters are still C and E.

Step 2: the quality

Now count half steps to tell apart intervals with the same number. Unisons, 4ths, 5ths and octaves are perfect. 2nds, 3rds, 6ths and 7ths come in a major and a minor size. A perfect or major interval made a half step wider becomes augmented; a perfect or minor interval made a half step narrower becomes diminished.

Three whole-note harmonic intervals in treble clef: C4 with E4, C4 with E flat 4, and C sharp 4 with E4.
All three are 3rds, because each spans three letter names. C–E spans 4 half steps (major); C–E♭ and C♯–E span 3 (minor).
To find the quality, count every key after the lower note. From C to E: C♯ (1), D (2), D♯ (3), E (4). Four half steps make a major 3rd.

The common intervals up to an octave, with their half steps:

Simple and compound intervals

Intervals up to an octave are simple. Wider ones are compound: a 9th is an octave plus a 2nd, a 10th an octave plus a 3rd. Turning an interval upside down, so the lower note becomes the upper one, is called interval inversion.

Hearing intervals

Every interval also has a sound you can learn to recognize. Consonant intervals such as 3rds, 5ths and 6ths sound stable; dissonant ones such as 2nds, 7ths and the tritone sound tense. Recognizing intervals by ear is a core skill of ear training and relative pitch.

Name intervals on the staff with Name the intervals: the distance, keep the Intervals chart nearby, and train your ear with Hearing intervals.

Common questions

How do you identify an interval?

Count the letter names from the lower note to the upper one, counting both ends, to get the number (2nd, 3rd, 4th and so on). Then count the half steps between them to get the quality: a 3rd of four half steps is major, of three half steps minor.

What is the difference between a melodic and a harmonic interval?

A melodic interval is two notes played one after the other, as in a melody. A harmonic interval is two notes played at the same time. The interval's name is the same either way.

Practice it: free worksheets