Guitar Exercise: Thirds on Adjacent Strings (Key of C Major)

Updated 2023
Estimated time to read: 5 minutes

If you are struggling with playing chords past the fourth fret in the key of C major, this post is an essential first step in unlocking the guitar fretboard. Third intervals are in every major and minor chord, so becoming familiar with these will help you understand chord structures. These exercises are also great warmups.

Sections:

• Guitar Thirds Exercise on Adjacent Strings

• Important Practice Notes

• Thirds on Low E String and A String

• Thirds on A String and D String

• Thirds on D String and G String

• Thirds on G String and B String

• Thirds on B String and High E String

• Other Major Scales

• Wrapping it up

Guitar Thirds Exercise on Adjacent Strings

In this post we will be using the key of C major, and all the notes that are in the C major scale. This means that we are playing the naturally occurring notes in the musical alphabet and the natural major and minor thirds found in the scale.

Just like the name implies, we will be playing thirds up and down the fretboard on two strings that are next to each other. For example, the thirds will be played on the E string and the A string together.

Read more about major and minor third here: An Introduction to Guitar Intervals

Important Practice Notes

Do not rush learning or playing these thirds up and down the fretboard. Take your time and be purposeful about your finger positioning and eliminate all buzzing. Pick the strings with your thumb and first finger simultaneously or use a pick to play the two strings together.

You can easily spend an entire practice session on one string pair, so do not feel the need to rush to the other strings. Come back to this lesson to review one or more of these exercises. Remember, the point of this exercise is to be intentional about each third interval and to play as clean and clear as possible.

Thirds on Low E String and A String

We know that the notes in the C major scale are all the natural notes, so we will follow the notes in the scale all the way up the fretboard with their accompanying thirds on the A string.

We will start with the first note on the low E string that has a naturally occurring third above it on the A string. This starting note on the E string is an F note on the first fret. Since a third above F is A, we can play the open A string at the same time. Continue up the fretboard until you get to the 12th fret.

Once we get to the 12th fret, we can take a quick pause and return down the guitar fretboard, playing each third interval in descending order until we end on the starting third of F and A.

Thirds on A String and D String

The first note on the A string in the C major scale is A, however the next string isn’t C, but D, so we need to choose the next note after A, which is B.

The B note is on the second fret of the A string and its third is D. We can play the open D string along with the B.

Continue up the A and D strings following the natural notes in C major.

Once we get to the 12th fret, we can take a quick pause and return down the guitar fretboard, playing each third interval in descending order until we end on the starting third of B and D.

Thirds on D String and G String

A third above D is F. Since that note isn’t available on the G string in the first few frets, we will select the next note, E. A third above E is G so we can use the open G string in this interval and go up from there.

Once we get to the 12th fret, we can take a quick pause and return down the guitar fretboard, playing each third interval in descending order until we end on the starting third of E and G.

Thirds on G String and B String

Once we get to the B string, our thirds interval patterns change a little. Instead of having to start on the next note in the scale, we can use both open strings, G and B, since they are a major third apart.

As you play the thirds on these strings, notice how the finger positions are a little different. This is because the strings are tuned a third apart instead of a fourth.

Once we get to the 12th fret, we can take a quick pause and return down the guitar fretboard, playing each third interval in descending order until we end on the starting third of G and B.

Thirds on B String and High E String

Finally, we get to the last string pair for playing thirds on adjacent strings. The strings are a tuned a fourth apart again so we are back to the same issue as before. A third above B is D (which isn’t available on the E string) so our starting note will be C, using the open E string.

Once we get to the 12th fret, we can take a quick pause and return down the guitar fretboard, playing each third interval in descending order until we end on the starting third of C and E.

Other Major Scales

This lesson applies to any key or scale. To read more about the major scale formula for learning other major scales, check out this post: A Complete Rundown of the Major Scale Formula

Wrapping it up

Each string pair of thirds up and down the fretboard is an exercise in itself. Do not feel the need to rush through each string. Instead be intentional about your practice.

To make these exercises more impactful, say the note names in each third interval in addition to playing them on your guitar. Even though saying the note names each time you play takes a little longer for the exercise, you will begin to learn where the notes are on each string a lot faster.