An interval is a measure of distance between two pitches.

Naming an interval

There are two steps to labeling an interval. The first step is to name the interval according to its distance on the staff.

To measure an interval between two notes, count the lines and spaces of the staff, counting the first note as one. Consider this example:

The F is 1. The line above F is 2. The A is 3. Therefore, this interval is a third.

Here are all of the basic intervals:

Classifying an interval

Intervals are labeled not only by their number, as illustrated above, but also by their type. There are five different types of intervals:

perfect - octaves, fifths, fourths, and unisons can be perfect.
major - seconds, thirds, sixths, and sevenths can be major.
minor - seconds, thirds, sixths, and sevenths can be minor. Minor is smaller than major.
augmented - an augmented interval is a little bit larger than a major interval.
diminished - a diminished interval is a little bit smaller than a minor interval.

To determine the interval type, count the number of half steps that make up the distance. This time, do not count the first note as one. For example:

F-F# is 1, F# to G is 2, G to G# is 3, G# to A is 4.

Here is a chart to help you memorize the half steps in each interval.

	Perfect	Major	Minor	Augmented	Diminished
Unison	0
Second		2	1	3
Third		4	3
Fourth	5			6
Fifth	7				6
Sixth		9	8
Seventh		11	10
Octave	12

Harmonic and melodic intervals

Intervals may be referred to as harmonic or melodic. Harmonic intervals occur when the two notes are played simultaneously. Melodic intervals occur when one note is played after another (as in a melody.)