Musical Intervals: A Comprehensive Guide

Whole and half steps

Intervals are a core concept in music, but the two intervals that are most relevant to understanding scales are whole and half steps.

Half Steps

A half step, also called a semitone, is the smallest musical interval in existence. This is the span from one note to an adjacent note.

On a keyboard, every key is a half-step from the adjacent key.

B and C are adjacent on the keyboard, and are therefore a half-step apart

On a guitar, any two adjacent frets on the same string are a semitone apart. Two notes on different strings can also be a semitone apart. For example, the fifth-fret Low E string is a half-step below the first-fret A-string.

B and C (second and third-fret A-string) are on adjacent frets on the same string, and are therefore a half-step apart.

Semitones are key to understanding musical intervals, as any musical interval can be measured as a specific number of half-steps.

For example, the interval from C to G is known as a perfect fifth (we’ll cover this in more depth later). However, let’s think about this interval in terms of semitones:

  • C to C# is one semitone.
  • C# to D makes two.
  • D to D# is three.
  • D# to E is four.
  • E to F is five.
  • F to F# is six.
  • Finally, F# to G is seven.

In other words, a perfect fifth can also be viewed as an interval of seven semitones. This applies to all intervals; half-steps are the foundation of musical intervals.

Whole Steps

A whole step is an interval of two semi-tones, and is also known as a tone.

On a piano a key is a whole step away from another if there is one key in between them.

Alternatively, you can think of a it as being two half-steps away.

B and C# are two half-steps away on the keyboard, and are therefore a whole-step (tone) apart

Simple Intervals

All intervals are named for their relation to the tonic, or starting note. The intervals in this section are the most commonly used, and are known as simple intervals. These are intervals that are within an octave (or eighth) of the root note.

If the root note of an interval was C, the interval between that C and the C above it, or any note in between, would be considered simple.

We’ll look at every interval, from a half-step apart to a full octave, in order of increasing distance.

Second

Any interval from one letter note to an adjacent one is considered a second. For example, from C to Db is an ascending second, as is D to E.

Remember that the musical alphabet spans from A to G and then loops back around, so an interval from G to A is also a second since these two notes are adjacent in music.

There are two kinds of seconds: Major and minor.

Minor Second

A minor second
A minor second

A minor second is formed by two notes a semitone apart, and is the smallest musical interval. The interval from C to C# is a minor second.

Major Second

A major second musical interval
A major second

The major second is the next-largest musical interval, with a distance of two semitones.

Augmented Second

augmented second musical interval
An augmented second

An augmented second is a span of three semitones, such as the interval from C to D#.

Third

A third occurs when two notes are two letter names apart. For example, from A to C is a third, as is the interval from C to E.

Minor Third

A minor third
A minor third

The minor third, like the augmented second, is an interval of three semitones. The difference is purely notational: Since C and D are adjacent letters, C to D# is a second, whereas C to Eb is a third.

Keep in mind, D# and Eb are enharmonic (the same note), so the actual interval is identical.

Major Third

A major third

One half-step up from a minor third, the major third is an interval of four semitones. The interval from C to E is a major third.

Fourth

A fourth is formed by two notes that are three letter names apart. For instance, the intervals between C and F, G and C, and A# and D are all fourths.

Diminished Fourth

Diminished fourth musical interval
A diminished fourth

Just as an augmented second and minor third are the same, a diminished fourth is identical to a major third: It’s an interval of four semitones. In this instance, though, the notes are three letter-names apart rather than two (Fb and E are enharmonic).

Perfect Fourth

perfect fourth musical interval
A perfect fourth

The perfect fourth is an interval of five semitones, such as the one from C to F or F to Bb.

Augmented Fourth

augmented fourth musical interval
An augmented fourth

An augmented fourth spans six semitones. This musical interval is also sometimes referred to as a tritone, so named because it’s the equivalent of three adjacent whole steps (or tones).

Fifth

The fifth is, the interval in which one note is on the fifth sequential letter from another. Some examples include the interval between F and C, D# and A, and C and G.

The sequence of C, D, E, F, G goes through five adjacent letters, and so the interval from C to G is a fifth.

Diminished Fifth

Diminished fifth musical interval
A diminished fifth

The diminished fifth is enharmonic with the augmented fourth: it’s also a tritone, an interval of six half-steps.

Perfect Fifth

perfect fifth musical interval
A perfect fifth

A perfect fifth occurs between two notes that are seven semitones apart. Some examples of perfect fifths include the intervals from C to G, A to E, and B to F#.

Augmented Fifth

augmented fifth musical interval
An augmented fifth

The augmented fifth is one half-step farther than a perfect fifth, or an interval of eight semitones.

Sixth

As you probably guessed, a sixth is an interval between notes that are five letter-names apart, such as C and A, E and C, or G and E.

Minor Sixth

minor sixth musical interval
A minor sixth

The minor sixth is the smallest sixth interval, a span of eight semitones. It’s enharmonic with the augmented fifth.

Major Sixth

major sixth musical interval
A major sixth

One half-step up from the minor sixth is the major sixth, an interval of nine semitones.

Seventh

The penultimate simple interval, the seventh occurs between a root note and the seventh note in a consecutive sequence.

Examples of seventh intervals include that from C to B, E to D, or F# to E.

As with every other interval, we see that the first and seventh note of a major or minor scale produce an interval of a seventh.

Since the musical alphabet is circular, you can also think of a seventh as the interval from the root note to an octave above the previous letter.

That may seem complex, but it’s actually quite simple. Let’s consider an example.

We know that the interval from C to B is a seventh because we can think of the sequence of the notes between these two:

C, D, E, F, G, A, B

In other words, B is the seventh letter in the sequence, and thus forms a seventh.

But we could have also started with C and gone to the left…

C, B

…And gotten the same result. This is much quicker, but it’s important to remember that you have to add an octave. In other words, this interval is not a seventh:

whereas this one is:

Diminished Seventh

Diminished Seventh musical interval
A diminished seventh

A diminished seventh is formed by two notes that are 9 semitones apart.

Minor Seventh

minor seventh musical interval
A minor seventh

A minor seventh is formed by two notes that are 10 semitones apart.

Major Seventh

Major seventh
A major seventh

A half-step above the minor seventh comes the major seventh, an interval of 11 semitones.

Eighth (Octave)

The eighth, also known as the octave, is the largest simple interval. It spans from one letter note to the next instance of that note.

For instance, the interval from one C to the next one is an octave.

Diminished Octave

diminished octave musical interval
A diminished octave

The diminished octave is enharmonic with the major seventh; they’re the same interval, just notated differently, a span of 11 semitones. To look at it differently, a diminished octave is the interval from a note to its flat an octave above (i.e. from C to Cb).

Perfect Octave

perfect octave musical interval
A perfect octave

The most common quality of octave by far, the perfect octave is formed by two notes that are 12 semitones apart (this is why the guitar fretboard has two dots at the twelfth fret).

Augmented Octave

augmented octave musical interval
An augmented octave

Last but not least, we have the augmented octave, an interval of 13 semitones, or the interval from a note to its sharp an octave above.

Compound Intervals

Anything greater than an octave is considered a compound interval. You might find it easier to think of these in terms of their corresponding simple interval. To do this, simply subtract seven from the interval.

Here’s an example: Consider a major ninth starting on C. Let’s count it out: C, D, E, F, G, A, B, C, D. Since D is the ninth note in the C major scale, this is the note that gives us a major ninth above C.

If we take 9-7, we get 2. In other words, a major second is the same as a major ninth, just an octave higher.

This applies to any interval: a minor tenth is just a minor third raised an octave.

Compound intervals typically only go up to fifteenths (an interval of two octaves) and they rarely even make it that high. Focus on becoming comfortable with all of the simple intervals first and use the subtract-seven rule to figure out the rest.

A Graph of the Musical Intervals

We’ve put together a graph of every musical interval through the augmented octave. Above this, just use the subtract-seven rule to figure out what notes an interval is made up of.

Number of SemitonesInterval NameExample
1Minor SecondC to Db
2Major SecondC to D
3Augmented SecondC to D#
3Minor ThirdC to Eb
4Major ThirdC to E
4Diminished FourthC to Fb
5Perfect FourthC to F
6Augmented FourthC to F#
6Diminished FifthC to Gb
7Perfect FifthC to G
8Augmented FifthC to G#
8Minor SixthC to Ab
9Major SixthC to A
9Diminished SeventhC to Bbb
10Minor SeventhC to Bb
11Major SeventhC to B
11Diminished OctaveC to Cb
12Perfect OctaveC to C
13Augmented OctaveC to C#
Garrison Bates
Garrison Bates loves music. He started playing and learning piano at age four and guitar at eleven. He began studying music theory when he was young and especially enjoys rock 'n' roll, old country, and folk music.
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