Master Guitar Theory: 4-Step System for Rapid Progress

Want to learn guitar theory? In this lesson, we’ll show you everything you need to know about guitar theory.

In this free guitar lesson you will learn:

  • 5 must-know lessons which will turn you a guitar theory master.
  • 3 essential tips for understanding major and minor scales.
  • 2 top chord construction secrets.
  • 3 guitar theory hacks which will enhance your musicality.

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What Is Guitar Theory?

Guitar theory is essential to know if you want to become an advanced guitarist, guitar theory shows you HOW everything works in the guitar world.

There are 4 things you need to know about guitar theory, these are:

  • Guitar scales and intervals.
  • Chord construction.
  • Understanding musical keys.
  • How to use all of these elements in your playing!

Guitar theory can be a daunting prospect for many guitarists. However, it’s vital to know if you want to take your playing to the next level.

Guitar theory is a HUGE subject, so don’t expect to learn it all in one go. Take it one step at a time.

Put this lesson in your bookmarks and refer back to it as you progress in your theory journey.

Learning an instrument benefits your brain and body. Find out how in this article by The Guardian:Want to ‘train your brain’? Forget apps, learn a musical instrument

Guitar Scales

The first step in understanding guitar theory is learning guitar scales. A scale is a group of musical notes.

In music we have two types of scales, those are:

  • Major scales.
  • Minor scales.

Both scales are used to create different types of sounds, major scales have a ‘happy’ sound and minor scales have a ‘sad’ sound.

They both have their uses in all kinds of music.

In today’s lesson we’re going to talk about our scales in the key of ‘C’.

Want to learn about the key of ‘C’? Go here: Understanding the chords in the key of C

The Major Scale

The key of C has no sharps or flats. Therefore, if we’re playing in the key of C, that means the notes are:


Here’s a C major scale on guitar:

guitar theory

To learn this scale, go here: C Major Scale On Guitar

Because there are no sharps or flats, the key of ‘C’ is a nice and easy key to think in.

The Minor Scale

In music, we have relative scales. Relative scales, are scales in the same key which start off of different notes.

So for example, our C major scale contains the notes:


However, to create a minor scale in the key of C, we have to start off of a different root note.

That root note is ‘A‘, so our minor scale now has the notes:


Here’s the A minor scale on guitar:

guitar theory

To learn this scale, go here: Learn Guitar Scales In 8 Easy Steps

Can you see, how the scale has a different root note, yet it uses the EXACT same notes as the C major scale?

This is a classic example of a relative minor scale.

Download our lead guitar cheat-sheet to make things easier

It's hard to understand which scales work with which keys.

So we created a cheat-sheet! A key and scale-finder that you can use again and again.

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Each note in the scale has a relationship with the root note. These are know as ‘intervals’.

An interval is the gap between each note of the scale.

When we talk about intervals, we tend to talk about their relation to the root note.

This means, that if our root note is ‘C’, the rest of the notes in the scale have an individual relationship with the note C.

Like this:

guitar theory

We can apply a similar concept to the minor scale, however this time the minor scale has a different root note, so this means that the perspective of the intervals change.

Like this:

guitar theoryTry and use your instrument to understand guitar theory.

For example when you play your major or minor scale, you should:

  • Visualise what each interval looks like compared to the root note.
  • Listen to what each each interval sounds like compared to the root note.

When we learn a scale, it’s easy to find the root note and blast through the pattern without even thinking about what any of the notes are called.

Try this as a challenge:

  • Play the C major and A minor scales and name the notes as you play the scale.
  • Play the C major and A minor scales and name the intervals as you play the scale.

It’s important to understand this, as intervals and scales help us to construct chords.

guitar theory

Chord Construction

Understanding chord construction is really useful when understanding guitar theory.

This helps us to understand:

  • How chords are built harmonically.
  • Why certain notes of a chord work better with certain notes in a scale.

Guitar chords are built from each note in the scale. Here’s a really simple way to build chords off of scale. In today’s lesson, we’re going to apply this to the C major scale.


Pick your root note, this can be ANY note in the scale. However, for today’s lesson we’re going to use the note ‘C’.

guitar theory

After we’ve picked our root note, we skip across two notes to the 3rd note.

This means we now have the note ‘E’.

guitar theory

After this, we move across two notes again to the note ‘G’.

guitar theory

Therefore the notes in a C chord, are the note C, E and G.

The notes we have chosen are the 1st, 3rd and 5th note in chord. This is what’s known as a triad.

All major and minor chords, are created by using the 1st, 3rd and 5th notes. To change the chord, we just change the root note.

Like this:

guitar theory

You can build a chord off of each note in the scale. However, for each note in the scale, we get a different chord type.

So for notes:

  • 1, 4 and 5 we have major chords.
  • 2, 3 and 6 we have minor chords.
  • 7 we have a diminished chord.

This means in the key of C, notes 1, 4 and 5  are C, F and G. Therefore the chords are  C major, F major and G major.

The 2nd, 3rd and 6th notes are D, E and A. Therefore the chords are D minor, E minor and A minor.

The seventh note in a C major scale is B, so we have B diminished.

Now we understand how chords are built, lets take a look at how this works in a key.

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