Intervals in Music

Step 1: count the letters

Count the letter names from the lower note to the higher one, counting both notes. C up to G is C, D, E, F, G: five letters, so it’s a 5th. C up to the next C is eight letters: an octave.

On the staff you can see the number without naming the notes:

• A line to the very next space (or a space to the next line) is a 2nd.
• A line to the next line, or a space to the next space, is a 3rd.
• Odd intervals (3rds, 5ths, 7ths) go line to line or space to space. Even ones (2nds, 4ths, 6ths, octaves) go from a line to a space.

Sharps and flats never change the number. C to E♭ and C to E are both 3rds, because the letters are the same.

Step 2: count the half steps

Two 3rds can be different sizes. Count the half steps, every piano key you move to, black or white:

• C to E is 4 half steps: a major 3rd.
• C to E♭ is 3 half steps: a minor 3rd.

Intervals chart

Every interval from the same note up to the octave, with its usual short name:

Half steps	Interval	Short	From C
0	Unison	P1	C–C
1	Minor 2nd	m2	C–D♭
2	Major 2nd	M2	C–D
3	Minor 3rd	m3	C–E♭
4	Major 3rd	M3	C–E
5	Perfect 4th	P4	C–F
6	Tritone	A4 / d5	C–F♯ or C–G♭
7	Perfect 5th	P5	C–G
8	Minor 6th	m6	C–A♭
9	Major 6th	M6	C–A
10	Minor 7th	m7	C–B♭
11	Major 7th	M7	C–B
12	Octave	P8	C–C

Major, minor and perfect

• 2nds, 3rds, 6ths and 7ths come in two sizes: major, and minor, which is a half step smaller.
• Unisons, 4ths, 5ths and octaves come in one usual size, called perfect.
• An interval a half step bigger than major or perfect is augmented; a half step smaller than minor or perfect is diminished. The one you’ll meet most is the tritone, six half steps, which is an augmented 4th (C–F♯) or a diminished 5th (C–G♭) depending on the spelling.

How to identify any interval

1. Find the number by counting letters (or lines and spaces).
2. Imagine the major scale of the lower note. If the top note is in that scale, the interval is major (for 2nds, 3rds, 6ths and 7ths) or perfect (for 4ths, 5ths and octaves).
3. If the top note is a half step lower than the scale note, a major interval becomes minor, and a perfect one becomes diminished.

Example: D up to F. Letters D, E, F: a 3rd. D major has F♯, but this is F, a half step lower. So D to F is a minor 3rd.

Hearing intervals

Many people learn to hear intervals from tunes they know. Each of these has the interval near its start:

Interval	Tune	Listen between
Major 2nd	Happy Birthday	“-py” and “birth”
Major 3rd	When the Saints Go Marching In	“Oh” and “when”
Perfect 4th	Here Comes the Bride	“Here” and “comes”
Perfect 5th	Twinkle, Twinkle, Little Star	the first “-kle” and the second “twin”
Octave	Somewhere Over the Rainbow	“Some” and “where”

To hear any interval on its own, tap its two notes one after the other on the free online pitch pipe. To check an interval’s name, tap its two notes into the chord identifier; add a third note and it names the chord.

Why intervals matter

Intervals are the building blocks of everything else in music theory. A major scale is a pattern of 2nds. Chords are stacked 3rds: a major chord is a major 3rd with a minor 3rd on top, and a minor chord is the other way round.

Practice intervals

Trebly’s Intervals lesson has you name intervals on the staff from a 2nd to an octave, build them by tapping the line or space, and count half steps on the keyboard to tell major 3rds from minor 3rds. Every interval plays as you answer.