What are Music Intervals?

What is an interval? What do semitones and half steps mean? And what in the world is an augmented interval?

Intervals are some of the most important details in a musical piece. Without them, we wouldn’t have chords, scales, or even melodies. Intervals are one of the foundations of music. 

In today’s post, we’ll define “interval” and take a look at how it works in music. Then we’ll go over some of the different types of music intervals, including unison, perfect, and major/minor intervals. 

First off, let’s define the word interval, and what it means in music.

What is an Interval in Music?

In music, an interval is a way to measure the space between two notes.

If two notes have a huge distance between them, their pitches will have a greater distance as well. 

For example, a middle C sounds very different from an A6. 

However, a middle C and a C# have a much smaller interval, so the pitches will sound very close to each other.

We use three different words to describe an interval:

  • Distance
  • Quality (the specific type of interval)
  • Harmonic or Melodic

Types of Intervals

The simplest type of interval to learn is the perfect unison.

What is a Unison Interval?

If two instruments play the exact same note, this is called unison.

Unison intervals are shown by two notes written next to each other, if the interval is harmonic– more on that later. 

Most types of intervals are written as a number. For example, a major third, or a perfect fourth. A unison interval is shown as a zero, because there is no difference between the notes.

Perfect Unison

Now that we’ve talked about unison, let’s take a look at semitones (half steps) and tones (whole steps).

Semitones and Tones

You might know them as semitones and tones, or you might use the American terms and say half steps and whole steps. 

Semitones and tones are the building blocks of intervals. 

Remember, an interval is the distance between the notes. Semitones and tones are the smallest intervals, and we use them to make up different types of chords and scales. 

Here is a chart of tones (T) and semitones (S) in the C major scale:

Tones and semitones (half steps and whole steps) in C major scale
Tones and Semitones in C major

What are Semitones?

The smallest interval in Western music is the semitone, or half step. 

A semitone is the very next note. For example, on a piano, C to C# is a semitone. So is E to F.

Semitones can go up or down, but they are always the very next note. B to C is a semitone, but C to D is not, because going from C to D would skip C#. 

Basically, semitones are two notes that are right next to each other on the piano.

The word “semi” actually means half. (Just like semiquaver means half a quaver note.) So a semitone is half a tone.

Tones

A tone (also called a whole step) is worth two semitones. 

For example, C to C# is one semitone, and C# to D is one semitone. If you put them together, C to D is a tone. 

Remember, two semitones make one tone. So C# to D is a semitone, but C# to D# would be a tone.

It’s important to know about tones and semitones, because these are the building blocks to understanding the other types of intervals.

Names of the Intervals

Now that we’ve learned about semitones and tones, let’s talk about bigger intervals.

As you might have guessed, there are lots of different intervals, and they all have different names. We count how many letter notes are in between two notes. Then we use that number as the interval name.

For example, from C to D, there are two letter notes between them: C and D. So this interval is called a 2nd. 

However, from C to E has three letter notes (C, D, and E). This is a 3rd. 

C to F has four letter notes, so it’s a 4th. (C, D, E, and F.)

C to G has five letter notes. It’s a 5th. (C, D, E, F, and G.)

Are you starting to see a pattern here?

C to A is a 6th. (C, D, E, F, G, A.) 

Next we have C to B, which is seven notes apart (C, D, E, F, G, A, B), and we call it a 7th. 

And finally, C to C, which is eight notes. Technically, this interval is an eighth, but we often call it an octave. The word octo- means eight, like an octagon or an octopus. So an octave is 8 notes apart.

Interval Quality

Next, let’s talk about interval quality. 

Remember our list of ways we refer to intervals? 

  • Distance
  • Quality (the specific type of interval)
  • Harmonic or Melodic

The numbers we just mentioned have to do with the distance between the notes. Now, let’s talk about the interval quality.

What is interval quality? 

Let’s say that we have two intervals that are both 4ths. One is C to F, one is C to F#. 

Both intervals have four letter notes between them (C, D, E, F), but they still sound different.

This is where interval quality comes in.

What are the Types of Interval Quality?

The five different types of interval quality are:

  • Perfect intervals
  • Major intervals
  • Minor intervals
  • Augmented intervals
  • Diminished intervals

We’ll go over each of these interval types, but before we get started with perfect intervals, let’s take a moment to review the major scale. 

Starting from the tonic (starting) note, every note in the major scale is either a perfect interval or a major interval. 

Here are the intervals in a major scale:

perfect intervals and major intervals (image by Wikimedia Commons)

Perfect Intervals

There are three intervals that we call perfect intervals:

  • Perfect 4th
  • Perfect 5th 
  • Perfect octave (8th)

Perfect intervals on music staff (by Wikimedia Commons)

This means that the top note of the interval is in a major scale. 

If the 4th is in a minor scale, it’s not a perfect 4th.

For example, C to F# is not a perfect 4th, because F# is not on the C major scale. 

(C to F# would technically be an augmented 4th. More on that later.)

Again, the perfect intervals are perfect 4th, perfect 5th, and perfect octave. But they are only perfect if the notes are in a major scale.

Major Intervals

The four major intervals are:

  • Major 2nd
  • Major 3rd
  • Major 6th
  • Major 7th

The major intervals are essentially the same as perfect intervals, just with different numbers. 

If the top note is in a major key, and the interval is a 4th, 5th, or octave, it’s a perfect interval. 

If the top note is major, but the number is not a 4th, 5th, or octave, it’s a major interval.

So the pattern of major and perfect intervals is:

  • Major 2nd
  • Major 3rd
  • Perfect 4th
  • Perfect 5th
  • Major 6th 
  • Major 7th
  • Perfect 8th
  • Perfect unison

This pattern is fairly easy to remember. Major, major, perfect, perfect. Major, major, perfect, perfect.

Remember, this only works if the lower note is the tonic note and the higher note is on the major scale. 

Again, C to G would be a perfect 5th. C to Gb would not be a perfect 5th, because Gb is not a note on the C major scale. Instead, C to Gb would be classified as a minor interval.

Quick Recap

I know this is a lot of information, so let’s do a quick recap to remember what we’ve learned so far.

A unison interval is where two instruments or voices play/sing the same note at the same time. This is perfect unison. 

We use numbers to measure the distance between two notes in an interval. To do that, we count the number of letter notes (C, D, E, etc) between the notes. So from D to A is a 5th (D, E, F, G, and A is five notes). 

If the upper note is in the lower note’s major scale, the interval is either major or perfect.

  • If it’s in the major scale and 4th, 5th, or 8ve/octave, it’s a perfect interval.
  • If it’s in major scale and 2nd, 3rd, 6th, or 7th, it’s a major interval.

Minor Intervals  

If we take any of the major intervals, and make them one semitone smaller, we now have a minor interval. 

For example, C to G is a perfect 5th, but if we flatten the G to a Gb, we get a minor 5th.

This does not work on perfect intervals, just the major intervals. So there are only four minor intervals:

  • Minor 2nd
  • Minor 3rd
  • Minor 6th
  • Minor 7th

Basically, a minor interval is like a major interval, but flat.

Here’s a chart of major (M) and minor (m) intervals in C major:

Major and minor intervals on the music scale (by Wikimedia Commons)
Major and minor intervals

We’ve talked about what happens when the top note of a major interval is flat. But what about a flat note in a perfect interval?

Diminished Intervals

A diminished interval is where we flatten a perfect interval (4th, 5th, or octave) by one semitone.

If we start with a perfect 4th of G to C, and changed the C to a Cb, we’d get a diminished interval.

G to Cb is still a 4th (G, A, B, C), but it’s no longer perfect. It’s a diminished 4th. 

We can also flatten minor intervals and make them diminished too.

For example, G to F is a major 7th. Lower it by one semitone and it becomes G to E, which is a minor interval. Then lower it by one more semitone, and it’s now G to Eb, which is a diminished 6th.

Same as a flattened top note changes major intervals to minor, a flat top note changes a perfect interval into a diminished interval.

Remember:

  • Perfect interval flattened by one semitone (half step) is a diminished interval
  • Minor interval flattened by one semitone is a diminished interval
  • Major interval flattened by two semitones (one tone) is a diminished interval. (One semitone turns it minor, two semitones makes it diminished.)

Augmented Intervals

So we’ve learned about major and perfect intervals, as well as what happens when you make them flat (minor and diminished intervals). 

What about if you make them sharp?

An augmented interval is when we increase the major or perfect interval by one semitone, without changing the letter name.

C to F, a perfect 4th, becomes C to F#, an augmented 4th. 

F to G (major 2nd) becomes F to G#, an augmented 2nd.

However, it doesn’t work if the letter name changes. For example, G to B would turn into G to C. That’s not an augmented interval.

With augmented intervals, it doesn’t matter if you start with a major or perfect interval. As long as the top note is one semitone higher, without changing the letter name, it’s an augmented interval.

Music Intervals Chart

To make things (hopefully) easier, here is a handy chart of all the different types of intervals, their abbreviations, number of semitones, and an example for each one.

IntervalAbbreviationSemitonesExample
UnisonP10C – C (same note)
Minor 2ndm21C – Db
Major 2ndM22C – D
Augmented 2ndA23C – D#
Minor 3rdm33C – Eb
Major 3rdM34C – E
Diminished 4thD44C – Fb
Perfect 4thP45C – F
Augmented 4thA46C – F#
Diminished 5thD56C – Gb
Perfect 5thP57C – G
Augmented 5thA58C – G#
Minor 6thm68C – Ab
Major 6thM69C – A
Minor 7thm710C – Bb
Major 7thM711C – B
Perfect 8ve (octave)P8 (or 8ve)12C – C2

Compound Intervals

Up until now, all the intervals we’ve looked at have been in one octave. 

Intervals in the same octave are called simple intervals. 

However, there are some intervals that are bigger than one octave. 

For example, middle C to F the octave above. 

Musicians use two different ways to name compound intervals. 

The first way is to figure out the interval if it were in one octave, then add the word “compound” in front of it. 

In our example, C to F is a perfect 4th. So C to the F an octave higher would be a compound perfect 4th.

Another option is to use numbers higher than 8. 

Remember, our simple intervals go up to the perfect 8ve, the octave? With this option, we simply keep counting higher. 9th, 10th, 11th, 12th, and so on.

9th, 10th, 11th, 12th intervals on music staff (image by Wikimedia Commons)

Our example of C to F one octave higher would be an 11th.

Harmonic vs. Melodic Intervals

So far, we’ve covered how to categorize intervals by distance (2nd, 3rd, etc) and by interval quality (perfect, major, minor, diminished, augmented, or compound). 

Now let’s take a look at the last way to categorize intervals: harmonic vs. melodic. 

(It’s worth noting that harmonic intervals and melodic intervals are different than harmonic and melodic minor scales. Even though we use the same words, the intervals and minor scales are totally different.)

Harmonic and melodic intervals on music staff (image by Wikimedia Commons)

Harmonic Intervals

Harmonic intervals are two notes that are played at the same time. 

This could be a chord played on the piano, or two voices singing different notes to the same rhythm. 

The notes are played in harmony, so we call these harmonic intervals.

Melodic Intervals

Melodic intervals are the opposite of harmonic intervals. 

When an interval is melodic, this means two notes are played one after the other. 

These notes could be part of a melody in a song. For example, the first two notes of “Amazing Grace” is a melodic interval, because the notes are played separately, back to back.

We use the terms harmonic and melodic to describe if the two notes in the interval are played at the same time or separately.

Conclusion

We hope this post is helpful to you as you learn about intervals in music! 

Remember, music intervals are categorized by three traits:

  • Distance (2nd, 3rd, etc)
  • Interval Quality (perfect, major, diminished, augmented)
  • Harmonic (two notes played at once) or melodic (two notes played back to back).

Do you have any questions about music intervals? Let us know in the comments!

Jessica Roberts
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