Musical Interval Theory

If you haven't yet learnt about intervals this page will help you.

What is an Interval?

In musical theory, an interval is the difference between two notes or pitches of sound.

The smallest interval from the chromatic scale is called a semitone, also known as a halftone, a semitone represents one fret on a guitar.

Now, if we move up (or down) 2 frets instead of one to play the next note, that distance is a called a Tone, also called a Full Tone, or whole tone
Thus a Tone is equal to 2 semitones - easy enough right?

Intervals are a very important part of music theory, and you need to learn a little about them for best results!

So to make things as simple to understand as possible let's look first at the Major scale

The Major Scale Intervals

You are probably familar with the term, but lets look at how the major scale is constructed using some notes from the chromatic scale and a pattern of tone and semitone intervals.

You will now see why intervals are important.
Any Major scale (in any key) is constructed using the following intervals...

T, T, S, T, T, T, S - that's a... tone, tone, semitone, tone, tone, tone, semitone

Now lets apply this pattern to the chromatic scale and see what notes we get.

Here's a reminder of the chromatic scale again...


To avoid confusion with sharps and flats, will use C major scale for this example because it has neither. (starting note C)
Here's our major pattern again T, T, S, T, T, T, S

Now starting from the key note, C, see if you can work out the notes of the scale.
using the major scale interval pattern.

If you got C,D.E,F,G,A,B, you were correct.

Therefore all or any of these notes may be used when playing in the key of C major because they all belong to the major scale in the key of C and will 'fit' or sound good, musically with each other, i.e. they will not sound 'discordant'.

In addition, chords belonging to a Major scale may also be played in any order and sound good.
You will also see later how chords are built using scale notes.

Note the key of C major is the ONLY key without any sharps or flats contained within the scale.

Note that tone and semitone intervals are different for every type of scale.


Intervals With Names

I've included this part because you will often see mention of the following in guitar books and magazines and other sources, it's worth learning them so you know exactly what it is being talked about.

These are the named intervals between the different notes on a major scale (once again we are using the C Maj scale)

C-C is the First note, usually just called 'the First' but properly called the Unison or Perfect Unison.
C-D is a Major 2nd
C-E is a Major 3rd
C-F is a Perfect 4th
C-G is a Perfect 5th
C-A is a Major 6th
C-B is a Major 7th
C-C is (up or down) is the Octave

The above list is simplified somewhat for beginners, you can see a complete table here
Well you can see that is fairly complicated way of naming the intervals, but now you know what that the distance is between notes in the major scale when you read something like... "a perfect 5th above A"

However intervals are a pretty important thing to know, as they will help you easily construct chords, even if you don't know them yet, and it will help you even more to know how these intervals actually sound when applied to a piece of music you know.

I found these very useful examples for you online, which give you a better idea of how intervals sound, using the first few notes of the popular songs listed,
If you sing, whistle or hum the tunes loudly you will clearly hear the intervals in action.
  • Unison - The same note repeated
  • Major 2nd - Happy Birthday
  • Major 3rd  - Oh When the Saints Go Marchin In
  • Perfect 4th - The Wedding March
  • Perfect 5th - Twinkle, Twinkle Little Star
  • Major 6th - My Way verse part...And now..
  • Major 7th - Somewhere over the Rainbow (1st & 3rd notes)
  • Perfect Octave - Some-where (over the Rainbow)
Another interval to be aware of, because you may well see it mentioned somewhere, is called a Tritone interval, which has two definitions, it comprises of three adjacent full tones or six semitone intevals... don't go there yet, it's too complicated :-) If you really want to find out why see this page.