A musical interval is the distance of pitch between two notes. They may be described as harmonic (the two notes heard simultaneously) or melodic (proceeding each other).

Figure 1: The interval Minor 6th.

To measure an interval's size, two factors are taken into account: quantity and quality.


An intervals quantity is written numerically (e.g. C to G is a 5th).

To identify an intervals quantity, simply add up the number of lines and spaces between the two notes, including the lines and spaces containing the notes themselves. For example:

Figure 2: Counting five steps from C to G makes a fifth.

The following is a list of different interval quantities available:

Quantity Diagram
Unison (uni)
Second (2nd)
Third (3rd)
Fourth (4th)
Fifth (5th)
Sixth (6th)
Seventh (7th)
Octave (8ve)

If our two notes are sitting on the same line or space, the interval is unison. If the interval is eight lines and spaces apart, it's an octave.


Interval quality is used to describe interval quantity (e.g. Major 3th). It's what gives an interval it's distinct sound.

While quantity is known by counting the number of lines and spaces written, quality requires counting the full amount of semitones from the first to second note. For example:

Figure 3: There are four semitones from F to A (F, F#, G, G#, A) which makes a Major 3rd.

An interval's quality may be described as one of the following terms:

- Major (maj.)
- Minor (min.)
- Perfect (perf.)
- Augmented (aug.)
- Diminished (dim.)

Because some intervals sound more harmonious than others, and others more perfected, it is categorized that 2nd's, 3rd's, 6th's and 7th's may be major or minor and unison's, 4th's, 5th's and octave's may be perfect.

This completes our vocabulary for standard intervals:

Interval Semitones
perf. uni 0
min. 2nd 1
maj. 2nd 2
min. 3rd 3
maj. 3rd 4
perf. 4th 5
tritone 6
perf. 5th 7
min. 6th 8
maj. 6th 9
min. 7th 10
maj. 7th 11
perf. 8ve 12

An interval six semitones in length is called a tritone, which is the same length as an aug. 4th or dim. 5th.

Accidentals may be used to sharpen or flatten either note of an interval and give it a new quality:

Figure 4: Five intervals with the same quantity, but different qualities.

When accidentals are used to alter an intervals quality, the following four rules are implied:

First rule: If any major interval is flattened by a semitone, its quality becomes minor.
Second rule: If any minor interval is sharpened by a semitone, it becomes major.
Third rule: If any major or perfect interval is sharpened by a semitone, it becomes augmented.
Fourth rule: If any minor or perfect interval is flattened by a semitone, it becomes diminished.

...and that completes our vocabulary for all intervals used in western music:

Interval Augmented Diminished Semitones
perf. uni *dim. 2nd 0
min. 2nd 1
maj. 2nd dim. 3rd 2
min. 3rd aug. 2nd 3
maj. 3rd dim. 4th 4
perf. 4th *aug. 3rd 5
tritone aug. 4th dim. 5th 6
perf. 5th *dim. 6th 7
min. 6th aug. 5th 8
maj. 6th dim. 7th 9
min. 7th aug. 6th 10
maj. 7th *dim. 8ve 11
perf. 8ve *aug. 7th 12
*aug. 8ve 13

* Not very usable.

All intervals that share the same row are enharmonic intervals because, although they differ from each other in name, they don't in number of semitones.

The following are some examples for your understanding:

Interval Inversion

An interval inversion is when either note is raised or lowered an octave to impose an entirely new interval:

Figure 5: A perf. 5th becomes a perf. 4th when inverted.

Compound Intervals

Compound intervals are those greater than an octave in length. They may increase their numeric quantity greater than 8 (e.g. maj. 9th), or simply be called a compound maj. 2nd.

Figure 6: A maj. 9th or compound maj. 2nd.

Interval Recognition (Songs)

It is commonly practised when recognising an interval by ear (aurally) to use the first interval, or one of the first intervals, of a song as a reminder. By singing the first two syllables of Amazing Grace (A-maz), it recalls we are hearing a perf. 4th.

The following is a list of songs which may be used as a reminder for each interval:

Interval Song
Ascending Descending
Unison O Little Town of Bethlehem O Little Town of Bethlehem
Min. 2nd


San Francisco (Left my heart)

I Remember You

I'm Getting Sentimental over You

Bye Bye Black Bird

Stormy Weather

It's Been a Hard Day's Night

Joy to the World

The Theme

Sophisticated Lady

Stella by Starlight

The Lady is a Tramp

Shall We Dance (The King and I)

Fur Elise

Maj. 2nd

Happy Birthday

Rudolf the Red Nosed Reindeer

Silent Night

My Funny Valentine

Body and Soul

Frere Jacques

Mary had a Little Lamb

Deck the Halls

Three Blind Mice

My Girl

The First Noel

Min. 3rd


Work Song


Georgia on my Mind

A Foggy Day


The Impossible Dream

Somewhere my Love

Brahm's Lullaby

Frosty the Snowman

What is This Thing Called Love?


When Irish Eyes are Smiling

Hey Jude

Peter Gunn

This Old Man

Star Spangled Banner

Maj. 3rd

Oh When the Saints

I Can't Get Started

While Shepherds Watched

Beethoven's Fifth


Giant Steps

Come Rain or Come Shine

Bessie's Blues

Perf. 4th

Amazing Grace

Here Comes the Bride


Someday my Prince Will Come

Hark the Herald Angels Sing

Oh Christmas Tree

We Wish You a Merry Christmas

All the Things


Song for my Father

Love me Tender

Auld Lang Syne

Shave and a Haircut

Oh Come All Ye Faithful

Valse Hot

Yardbird Suite

Softly, as in a Morning Sunrise

I Didn't Know What Time it Was

Almighty Fortress is Our God

Baseball Chant

Born Free

I've Been Working on the Railroad


The Simpsons

Maria (West Side Story)

Blue Seven

European Siren

Perf. 5th

Twinkle, Twinkle

Theme from 2001

Theme From Peanuts


7 Steps to Heaven

Have You Met Miss Jones?

The Way You Look Tonight

Mozart's Minuet in G


Min. 6th

Black Orpheus

Love Story (third and fourth notes)

Morning of the Carnival

Go Down Moses

The Entertainer (third and fourth notes)

Love Story Theme

Maj. 6th

My Bonnie Lies Over the Ocean

Jingle Bells - Verse - "Dashing Through the Snow"

You're a Weaver of Dreams

Nobody Knows the Troubles I've Seen

Over There

Gonna Lay Down My Sword and Shield

Min. 7th

There's a Place for Us (West Side Story)

Old Star Trek Theme

Somewhere (West Side Story)

I'll Close My Eyes

Watermelon Man

Theme from American in Paris

Maj. 7th

Cast Your Fate to the Wind


Theme from Fantasy Island


I Love You

"Hee Haw" From the Grand Canyon Suite

Perf. 8ve

Somewhere Over the Rainbow

A Christmas Song

Blue Bossa

There's No Business Like Show Business (Notes 2-3)

Willow Weep for Me

Also see Accidentals | Scales.

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