Intervals

An interval is the distance between two notes. Learn to see them as shapes on the staff and you stop reading music note by note: each next note is “up a third” or “down a step” from the last.

Number and quality

Every interval has a number: count the letter names from the bottom note to the top, both included. C up to G is C, D, E, F, G: five letters, a fifth. On the staff the number is all you need to read the shape: seconds step from a line to the next space, thirds go line to line, fifths skip a line.

The quality says exactly how many half steps it is. Seconds, thirds, sixths and sevenths come in major and minor (the minor one a half step smaller). Unisons, fourths, fifths and octaves are perfect. Any interval made a half step bigger than major or perfect is augmented; a half step smaller than minor or perfect, diminished. The one between a perfect fourth and a perfect fifth, six half steps, is the tritone.

Every interval in the octave

Interval	Short	Half steps	From C	Inverts to
Minor second	m2	1	C–D♭	major seventh
Major second	M2	2	C–D	minor seventh
Minor third	m3	3	C–E♭	major sixth
Major third	M3	4	C–E	minor sixth
Perfect fourth	P4	5	C–F	perfect fifth
Tritone	TT	6	C–F♯ / C–G♭	itself
Perfect fifth	P5	7	C–G	perfect fourth
Minor sixth	m6	8	C–A♭	major third
Major sixth	M6	9	C–A	minor third
Minor seventh	m7	10	C–B♭	major second
Major seventh	M7	11	C–B	minor second
Octave	P8	12	C–C	itself

Turn an interval upside down (move the bottom note up an octave) and you get its inversion: the half steps of the two add up to twelve, the numbers to nine, and major turns into minor (perfect stays perfect).

1 half stepMinor secondOne half step: the very next key. The smallest interval in Western music. 2 half stepsMajor secondTwo half steps, a whole step: the everyday step of scales and melodies. 3 half stepsMinor thirdThree half steps. The bottom of a minor chord, and the top of a major one. 4 half stepsMajor thirdFour half steps. The bright interval at the bottom of every major chord. 5 half stepsPerfect fourthFive half steps. Open, a little unresolved: Here Comes the Bride. 6 half stepsTritoneSix half steps, exactly half an octave. Restless, and it wants to resolve. 7 half stepsPerfect fifthSeven half steps. Strong, open and stable: Twinkle, Twinkle, Little Star. 8 half stepsMinor sixthEight half steps. A major third turned upside down; bittersweet. 9 half stepsMajor sixthNine half steps. Warm and open: My Bonnie Lies over the Ocean. 10 half stepsMinor seventhTen half steps. The seventh of a dominant seventh chord; bluesy and open. 11 half stepsMajor seventhEleven half steps: one short of an octave. Sharp, bright and tense. 12 half stepsOctaveTwelve half steps: the same letter name, higher or lower. Somewhere over the Rainbow.

Quiz: name every interval

Ten questions from the whole octave: name each interval on the staff, and play intervals above written notes on the piano below, a MIDI keyboard or your computer keys.

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Why intervals help you sight-read

Reading every note by name is slow. Readers who are fluent mostly read the distance from the note they just played: a step up, a third down, a fifth up. Your hand learns the matching shapes (a third is every other finger; a fifth is thumb to little finger in a five-finger position), so you can play the next note before you have named it. Practise intervals in real music with the free sight-reading exercises, and the guides on reading faster.

Questions

What is an interval in music?

The distance between two notes. It has a number (how many letter names it spans, counting both notes) and a quality (major, minor, perfect, augmented or diminished), which pins down the exact number of half steps.

How do you count an interval?

Count the letter names from the bottom note to the top one, including both: C up to E is C, D, E, three letters, a third. Then count half steps to find its quality: C to E is four half steps, a major third; C to E♭ is three, a minor third.

Which intervals are perfect?

The unison, fourth, fifth and octave. They have no major or minor version: make one a half step wider and it’s augmented, a half step narrower and it’s diminished.

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

A melodic interval plays its two notes one after the other, as in a tune; a harmonic interval plays them together, as in a chord.

Read intervals as shapes

Pianomi, a free sight-reading app for piano, brings in one interval at a time, fourths and fifths, thirds and sixths, then bigger leaps, in new music written at your level.

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