MUSIC
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MUSIC
THEORY
FOUNDATIONS

The complete guide to understanding what a music interval is

A music interval is vital to all melodies, chords and harmonies and will greatly improve your understanding of music theory. Intervals are the building blocks to all music. In this blog post we will explore what an interval is and how to label them properly.
What is an interval?
An interval in music is simply the distance between two notes/pitches. The distance between every single note, whether that be on top of each other or next to each other is an interval! Think about a simple scale, between every single note is an interval.

There are two different types of interval and these are harmonic and melodic. So what exactly is the difference between these two types of interval?

Harmonic Intervals and Melodic Intervals - What's the difference?
Melodic intervals are where the two notes are played successively, one after the other.
Harmonic intervals are where the two notes are played simultaneously, at the same time.

When labelling an interval there are two distinct steps you need to go through.

1. The distance of the interval - between the two notes.
2. The intervals quality - what descriptive word do we use for the interval?

Let's firstly visit how we work out what the distance in an interval is.

How to work out a music intervals number
An interval is always labelled with a number and in order to work this out we have to work out what the distance between the two notes is. Before doing this it is vital that you understand the different degrees of a scale:
This will make it much easier for you to work out an intervals number but will also help us out later as we move on through this explanation of intervals. As you can see the first note in a scale is labelled as number one. This means you will have to always include this first note whenever you are working out an interval.

Take a look at this melodic interval. We have the notes C and E, how do we work out the distance between these two notes correctly?

We will simply count up from C
As you can see, E is the third note of C major, making this interval of a third!

Below we have a harmonic interval. What is the distance between the notes G and D?

Again, we simply count up starting on G.
D is the fifth note of G major, making this an interval of a 5th.

It really is as simple as that. Always make sure that you start on the bottom or lowest note of your interval and count up in that scale including the starting note. It is important to note that even if the interval were to be written the other way around, with the higher of the two notes first, you would still start counting the interval from the lower note.

Before embarking on the rest of this blog post make sure that you know and understand exactly what a semitone and tone (whole steps and half steps) are as this will greatly help you when working out your intervals. Let's explore these now.

Semitones and Tones (Half Steps and Whole Steps)
Semitones and tones, otherwise known as half steps and whole steps, are the building blocks to all intervals. Understanding what a semitone and tone are will help you with understanding your intervals fully.

A semitone is the smallest interval you can have in western music (usually!). A semitone can also be referred to as half step.

A semitone is the note either above or below the original note. The easiest way to represent this is by looking at a piano keyboard. Highlighted is the note C, a semitone above this is C sharp or D flat and a semitone below is B natural or C flat.

Remember each note can have a different spelling but will sound the same, this is called an enharmonic equivalent.

A tone is made up of two semitones. A tone is also sometimes referred to as a whole step, it is also labelled as a major second but more on this later. The easiest way to show this is by looking at a piano.

A tone above C natural is D natural and a tone below C natural is B flat! Notice how it is not B natural as there is no black key between this.
Unison
Before moving onto how to label an intervals quality we need to look at when we have two notes that are exactly same. If two notes have the same letter then this is called playing in unison. Take a look at the example below.
Labelling the Music Interval quality
Now onto labelling interval qualities. Every single music interval we see not only has a number labelling the distance but it also has a quality. Interval qualities are important to understand as this will help you particularly when learning about chords.

There are five different interval qualities:

  • Perfect Interval
  • Major Interval
  • Minor Interval
  • Augmented Interval
  • Diminished Interval
These are important to distinguish intervals from each other. Take a look at the two intervals below. They both have the same distance, however, one of these notes includes a flat showing that they are not exactly the same. Naming the Interval quality helps us to distinguish between these two different intervals.
Major Intervals
In order to work out whether you have a major quality interval, you simply need to know whether the top note of the interval is in the scale of the lower note of the interval. Below you can see all of the intervals in the C major scale.
If we look at the notes C to A we know that this is the interval of a sixth, because A is the sixth note above C. But how do we know what the quality of this interval is?
We must ask ourselves if the top note is in the scale of the lower note. Is A natural in C major?

It most certainly is and therefore, this will be labelled a Major sixth.

An interval can be labelled major, if the top note of the interval is in the lower note of the interval.

You can also check that you have labelled your interval correctly by counting the semitones/half steps, if you feel comfortable with this. 

 

A major second will always be three semitones including the starting note

A major third will always be five semitones including the starting note

A major sixth will always be ten semitones including the starting note

A major seventh will always be twelve semitones including the starting note

Minor Intervals
The minor interval is one semitone/half step smaller than a major interval. In order to work this out you need to ask yourself if the top note is in the minor scale of the bottom note. You can also work out if the top note is in the major scale of the top note and simply bring the top note down by one semitone/half step.

Take a look at the two notes below, we have a C and an E flat.

The distance between these two notes is a third. Is E flat in C major?
E flat is not in C major. In C major scale we have an E natural. E flat is one semitone smaller than E natural making this a minor third.

Alternatively, if you are confident with your minor scales then you can ask yourself if the top note is in the lower note of your minor scale. For example, let's write out the C minor scale

Is E flat in C minor? Absolutely, making this a minor third.

You can also check that you have labelled your interval correctly by counting the semitones/half steps, if you feel comfortable with this. The minor interval always has the distance of 4 semitones.

Perfect Intervals
Not all intervals can be labelled major or minor. This is because some of the notes can be found in both the major and minor scales and therefore need a word that represents this.

The intervals of a second, third, sixth and seventh can all be considered major or minor.

However, the intervals of a fourth, fifth and octave can only be considered Perfect. You will never use the descriptive words major or minor with the intervals of a fourth, fifth and octave.

Take a look at the scales below, notice how the 4th, 5th and 8ve notes are exactly the same.

Let's take a look at the interval below. We have the notes C and F, the distance between these notes is a 4th.
Remember, the intervals of a 4th, 5th and 8ve are always perfect intervals. So this interval is a Perfect fourth.

If you have the interval of a 4th, 5th or 8ve and the note is in the major or minor scale of the lower note then each of these will be labelled perfect fourth, perfect fifth and perfect octave.

Make sure when working out your intervals you know whether you are looking at major/minor intervals or perfect intervals.

You can also check these intervals by looking at the number of semitones.

A perfect fourth has the distance of 6 semitones.

A perfect fifth has the distance of 8 semitones.

A perfect octave has the distance of 13 semitones.

Now let's look at augmented and diminished intervals:

Augmented Intervals
On top of the descriptions major, minor and perfect there are two more to understand if you are to master intervals in music theory.

In this section we will look at augmented intervals. An augmented interval is one semitone/half step larger than a major interval or a perfect interval.

Take a look at the augmented interval below. We have the notes G - C#, the distance between these notes is a fourth. Remember a fourth is considered a perfect interval if the top note is in the scale of the lower note. However, is C sharp in the G major scale?

There is a C natural in G major and therefore C sharp is one semitone/half step larger than C natural, making this the interval of an augmented fourth.

If the top note had been a C natural this interval would have been a perfect fourth.

Take a look at the piano below and you can see why C sharp is one semitone larger than C natural and therefore why this is the interval of an augmented fourth.

Diminished Intervals
Diminished Intervals move in the other direction. A diminished interval is one semitone/half step smaller than a minor interval and a perfect interval.

Take a look at the diminished interval below. We have a C natural and a G flat. The distance between these two notes is a fifth. A fifth is considered a perfect interval if the top note is in the major or minor scale of the lower note. However, is G flat in the C major scale?

There is a G natural in C major and therefore G flat is one semitone/half step smaller, making this the interval of a diminished fifth.

If the top note had been G natural then this would have been a perfect fifth.

Take a look at the piano below as you can see why G flat is one semitone lower than G natural and therefore why this interval becomes a diminished interval.

Simple Intervals and Compound Intervals
Before concluding this article on intervals there is one more aspect that you should know. In this post, most of the intervals we have looked at are all within and up to an octave. An interval that is an octave (eight notes in distance) or less is what we call a Simple Interval.
However, remember an interval is defined as the distance between two notes and in the music that you play you know that you see two notes with a distance greater than an octave! If your two notes are greater than an octave (eight notes) apart then these now are called compound intervals.

A compound interval is where the two notes in the interval are larger than an octave, remember an octave is eight notes. An interval larger than an octave would then venture into 9th, 10th, 11th etc. If you would like to know more about this then make sure to check out this blog post.

Hopefully this blog post has improved your knowledge on intervals and what they are, this topic is fundamental to all music theory and will help you as you progress onto all topics in music theory.
Author: Jade Bultitude
Jade is an experienced musician and teacher as well as being the founder of Music Theory Foundations.
She has been helping people learn music theory for more than 10 years from pre school children all the way to degree level studies.
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MUSIC
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