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Chord Functions in the Major Keys

Chords within a given key have a function, or role they play within the key. Understanding these chord functions can help you understand why some chord progressions sound good while others sound not so good.

In this lesson, we’ll go chord by chord in the key of G major and examine the make up of each chord and how its function is determined. Although we’re looking specifically at G major in this lesson, the information in this lesson woul

Chords in the key of G major

In order to build the chords of the G major key, you first need to start with the G major scale. Check out Building Chords from the Major Scale if you’re not sure how to harmonize the major scale. It’ll make this lesson easier to understand.

The diagram above lists all the notes of the key of G major. Above each note is a Roman numeral. This denotes two things: the scale interval and the quality of the chord. Uppercase numerals represent major chords, lowercase represent minor chords. The o denotes a diminished chord.

These intervals and chord qualities are always the same for every major key. In major keys, you have the following:

  • Major chords = I – IV – V
  • Minor chords = ii – iii – vi
  • Diminished chords = vii

Applied to the key of G major, you get the following chords:

  • G major
  • A minor
  • B minor
  • C major
  • D major
  • E minor
  • F# diminished

Playing through each of these chords sounds like the following:

Chord Families

Chord families are groups of chords that share the same function.

  • Tonic – stable, the tonal center, the resting point of a chord progression
  • Subdominant – these chords tend to move away from the tonal center, transitioning to the dominant function
  • Dominant – tension, these chords are the most unstable, need to resolve

Chords functions in the key of G major

Let’s now take a look at each chord in the key of G major and see which family each chord belongs to.

I Chord

I chord in a major key is a tonic chord

The I chord is the key, the tonal center. It is the tone in which the chord progression or melody centers around. It is composed of the 1st, 3rd, and 5th intervals of the scale.

Chord Family: Tonic

ii Chord

Subdominant chord function of the ii chord in a major key

The ii chord contains the 2nd, 4th, and 6th degrees of the scale. This chord doesn’t contain any notes from the I chord. This is a transitional chord, moving away from the tonal center.

Chord Family: Subdominant

iii Chord

Tonic function of the iii chord in a major key

The iii chord contains the 3rd, 5th, and 7th degrees of the major scale. This means the iii chord contains two notes from the I chord (3rd & 5th). In this case, it’s the B and D notes. Because of this, the iii chord functions as a tonic chord.

Chord Family: Tonic

IV Chord

Function of the IV chord in major keys

The IV chord is comprised of the 4th, 6th, and 1st intervals of the major scale. It contains only one note from the tonic chord , which is the 1st. This chord tends to move away from the key center toward the dominant chords.

Chord Family: Subdominant

V Chord

Dominant chord function of the V chord in major keys

The V chords contains the 5th, 7th, and 2nd degrees of the major scale, which means it contains one tonic chord tone (5th). The 7th degree gives this chord a good bit of instability. It’s what’s referred to as a leading tone. This leading tone is a half-step (semitone) below the tonic note, which creates a feeling of pull back to the tonic note, or the I.

For example, listen to the G major scale that stops on the 7th.

You can feel the tension and need to resolve back to the one. This leading tone gives the V chord a dominant function.

Chord Family: Dominant

vi Chord

vi chord tones in the major scale

The vi chord contains two tonic chord tones, the 1st and 3rd, and also the 6th degree. The two tonic tones give this chord a good bit of stability.

Chord Family: Tonic

vii Chord

Function of the vii chord in the major keys

The vii chord is a very unstable chord. It’s composed of the 7th, 2nd, and 4th degrees of the major scale, so it doesn’t contain any tonic chord tones. Also, the tonic of this chord is the 7th degree, which as we saw with the V chord, acts as a leading tone back to the I.

Chord Family: Dominant

Chord functions are summarized in the table below:

I, iii, viii, IVV, vii

Applying chord function to progressions

Understanding chord function can help you mold a progression and apply chords in a meaningful way. It can be used to create the tension and release that’s satisfying to the ear.

However, it’s important to keep in mind that in music theory, the music came first and the theory second. Assigning functions to different chords can make you feel like these are the rules and progressions should be written following these rules.

While this is a good rule of thumb to follow, you’ll find it isn’t always the case. Many, many songs break these rules. Treat chord functions more as a tendency than a hard, fast rule. Ultimately, what sounds good to your ear is the most important thing.

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