Chords - Introduction to Triads

Chords: Introduction to Triads

Now that you understand how intervals are named and measured, you can begin using them to build chords.

Chords are not random shapes on the guitar. They are created by combining notes at specific interval distances from a root note. The intervals included determine the chord's structure, sound and name.

In this lesson, you will learn how major, minor, diminished and augmented triads are constructed before looking at suspended chords, where the third is replaced by another interval.

Understanding these formulas allows you to build chords from any root note rather than relying only on memorised guitar shapes.

What Is a Triad?

A triad is the basic three-note chord structure used in tertian harmony. It contains three distinct notes:

Root–3rd–5th

The root gives the chord its letter name. The quality of the third and fifth determines the type of triad.

For example, a C major triad contains:

C – E – G

C is the root, E is the third and G is the fifth.

On guitar, the same triad can appear in different positions and inversions. A voicing may also double one or more notes while still containing only three distinct chord tones.

Triads form the foundation of many of the chords used throughout Western music.

Tertian Harmony

Major, minor, diminished and augmented triads are built using a system called tertian harmony.

Tertian harmony means building chords by stacking thirds. Starting from the root, we move to the note a third above it. From there, we move up by another third.

This produces the three-note structure C – E – G.

The interval formula can be applied from any root, but the resulting notes must still be spelled according to their function within the chord.

The four main tertian triad types stack thirds in these ways:

• Major: 1–3–5 — major 3rd + minor 3rd
• Minor: 1–♭3–5 — minor 3rd + major 3rd
• Diminished: 1–♭3–♭5 — minor 3rd + minor 3rd
• Augmented: 1–3–♯5 — major 3rd + major 3rd

In these formulas, 3 means a major 3rd, ♭3 a minor 3rd, 5 a perfect 5th, ♭5 a diminished 5th and ♯5 an augmented 5th.

Major and Minor Triads

Major and minor triads are the two most common triad types. Both contain a root, a third and a perfect fifth. The difference is the quality of the third.

Major Triads

A major triad uses the formula 1–3–5. It contains the root, a major 3rd and a perfect 5th.

When viewed as stacked thirds, C to E is a major 3rd and E to G is a minor 3rd. A major triad is therefore built by stacking a major 3rd followed by a minor 3rd.

Minor Triads

A minor triad uses the formula 1–♭3–5. It contains the root, a minor 3rd and a perfect 5th.

When viewed as stacked thirds, C to E♭ is a minor 3rd and E♭ to G is a major 3rd. A minor triad is therefore built by stacking a minor 3rd followed by a major 3rd.

Both major and minor triads contain the same root and perfect fifth. Lowering the major third by one semitone changes the major triad into a minor triad.

Diminished and Augmented Triads

By altering the 3rd, the 5th, or both, we create different triad qualities.

Together, major, minor, diminished and augmented chords form the four main tertian triad types.

Diminished Triads

The diminished triad is built from:

1–♭3–♭5

It contains the root, a minor 3rd and a diminished 5th. Compared with C major, both the third and fifth have been lowered by one semitone. Compared with C minor, only the fifth has been lowered.

When viewed as stacked thirds, C to E♭ is a minor 3rd and E♭ to G♭ is another minor 3rd. The diminished fifth gives the chord a tense and unstable sound.

Augmented Triads

The augmented triad is built from:

1–3–♯5

It contains the root, a major 3rd and an augmented 5th. An augmented triad begins with a major triad and raises the fifth by one semitone.

When viewed as stacked thirds, C to E is a major 3rd and E to G♯ is another major 3rd. The raised fifth gives the chord an open and unresolved sound.

Comparing the Four Main Triads

The four main tertian triads can be compared using their interval formulas:

The interval formula remains the same regardless of the root note. For example, every major triad uses 1–3–5, while every minor triad uses 1–♭3–5.

Suspended Chords

Suspended chords are three-note chords in which the 3rd is replaced by either a 2nd or a 4th. They are not conventional tertian structures because the 3rd is replaced rather than stacked above the root.

Because they contain no 3rd, suspended chords are neither major nor minor.

The word suspended is commonly shortened to sus. There are two main suspended chord types: Sus2 and Sus4.

Sus2

In a sus2 chord, the third is replaced by a major 2nd above the root.

Compared with C major, C – E – G, the E has been replaced by D. The absence of a third gives the chord an open sound that does not clearly establish a major or minor quality.

Sus4

In a sus4 chord, the third is replaced by a perfect 4th above the root.

Compared with C major, the E has been replaced by F. Once again, there is no third, so the chord is neither clearly major nor minor.

Suspended chords often create tension that can resolve when the 2nd or 4th moves to a 3rd, although modern music also uses them as independent chord colours.

Common Usage of Suspended Chords

The most common use of suspended chords is to create movement into a major or minor chord. A sus4 resolves when the 4th moves down to the 3rd, while a sus2 resolves when the 2nd moves up to the 3rd. The resolving 3rd determines whether the resulting chord is major or minor.

Like this:

Why These Formulas Matter

Learning chord formulas allows you to understand what a chord contains rather than only memorising a shape.

Once you know the root note and the required intervals, you can:

• Build the same chord type from any root.
• Identify the notes inside a chord.
• Alter chords deliberately.
• Find alternative chord voicings.
• Understand how different chord types are related.
• Apply chord structures across the fretboard.

In later lessons, you will build on these ideas by exploring chord inversions, extended chords and the way chords function within keys.

Use the Guitar Chord Finder and Analyser to map these chord tones and compare playable voicings, then continue to Seventh Chords to extend each triad.