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Lesson 3: Using intervals to find notes and chords in any key

Close up of a person strumming a guitar

When we’re working out a song, it’s important that we know what key it's in. If you’ve shied away from keys and scales in the past, because you think it means spending hours learning complex theory, don’t worry, I’m going to break this down for you and show you specifically, how to apply this to the guitar. You will learn

  • That there are seven individual notes in any key
  • That you can use these notes to understand which chords to play in a key
  • Chords 1, 4 and 5 in a major key will always be major
  • Chords 2, 3 and 6 in a major key will always be minor
  • Chords 7 in a major key will always be diminished

What is a musical key?

A key is a family of notes that sound good together.

We already know that there are 12 notes in the musical alphabet. You can start on any note (A-G) and work up all 12 notes until you return to the start (this is known as a chromatic scale).

When you play in a certain musical key, you identify which 7 of the 12 available notes in the musical alphabet you are going to use in your song together - either in your guitar solos, or to make up your harmonies and chords. Each key is made up of 7 main notes.

A key can be either major (happy sounding), or minor (sad sounding). Here, we’re going to look at major keys.

Finding the notes in any major key

To find the 7 notes in any major key we use the following pattern:

Whole step, whole step, half step, whole step, whole step, whole step, half step.

Sometimes you’ll hear this referred to as:

Tone, tone, semitone, tone, tone, tone, semitone.

So, following this pattern, let’s find all the notes in the key of C. Once we know the notes in the key, we can easily work out the chords to play on our guitar.

Remember, a whole step will take us two semi-tones forward, and a half step will take us a semi-tone forward.

C, whole step to D, whole step to E, half stept to F, whole step to G, whole step to A, whole step to B, half step back to C

You might have noticed that there aren't any sharp or flat notes in the key of C. That’s why it's often the first one that people learn. It's also called the natural key, or the people's key.

So that's step one. We've identified which seven notes we can play in the key of C. That approach will work for any major key you want to play in. So you can now work out the individual notes in any major key. The next step is to use this knowledge to identify the chords within the key.

Identify the chords in a major key

The good news is, once you've worked out your seven notes, that also tells you which chords to play in that key.

Notes 1, 4 and 5 will always be built out into major chords.

Notes 2, 3, and 6 will always be built out into minor chords.

The seventh chord in every major key is slightly different (it's diminished), but you don't need to worry about this for now. In fact, you'll probably never have to worry about it because it's used so infrequently!

So in our key of C major, the major chords will be C(1), F(4), and G(5).

The minor chords will be Am(2), Bm(3), and Dm(6).

This method works for every major scale.

And remember, you can play any song in any key as long as the intervals between the notes are the same.

Test your knowledge of major keys

Use the template in the PDF downloads to work out all the notes chords in every major key.

Once you’ve filled in it, you can keep this as a useful reference guide for when you’re working out songs in the future.

I've provided the answer sheets, but don't be tempted to cheat and look at these first. You'll need to keep these completed worksheet handy to help you with the next lessons.

Identify all the notes in each major scale - worksheet (PDF, 38KB)

Identify all the notes in each major scale - answer sheet (PDF, 36KB)

Identify the major and minor chords in each major key - worksheet (PDF, 35KB)

Identify the major and minor chords in each major key - answer sheet (PDF, 37KB)

Guitar practice journal

Download the Guitar Practice Tracker today. It will help to keep you motivated and give you a visual representation of your progress, and areas of focus throughout the year. 

A guitar journal will enable you to:
  • Set personalised goals and monitor your progress

  • Identify the number of hours or days you've spent on a particular skill
  • Provide a quick reference to the notes and chords in a particuar key
  • List the songs you know and sort by key, capo placement, artist, and chord progression
  • Link directly to your favourite YouTube videos and tutorials 

Go to Lesson 4: Harmony notes on guitar

If you enjoyed this free lesson, and you're able to, please 

Photo by 42 North