Triad

Three-note chord built from stacked thirds: major, minor, diminished, augmented.

Triads

A triad is the simplest complete chord — a stack of three distinct pitches built by stacking thirds (intervals of three or four semitones).

Triads form the harmonic foundation of Western music, from classical to pop, and are the basis of all extended and altered chords.

Each triad consists of:

1. Root — defines the chord’s name and tonal center.

2. Third — defines major (bright) or minor (dark) quality.

3. Fifth — stabilizes the chord, determining consonance or dissonance.

When written vertically, triads follow the tertian principle — every note is a third apart from the one below it.

Triad Types and Formulas

Triad Type	Interval Pattern (from Root)	Formula (Semitones)	Example (C Root)	Sound Character
Major	Root – Major 3rd – Perfect 5th	0 – 4 – 7	C–E–G	Bright, stable, consonant
Minor	Root – Minor 3rd – Perfect 5th	0 – 3 – 7	C–E♭–G	Dark, warm, introspective
Diminished	Root – Minor 3rd – Diminished 5th	0 – 3 – 6	C–E♭–G♭	Tense, unstable
Augmented	Root – Major 3rd – Augmented 5th	0 – 4 – 8	C–E–G♯	Lifting, unresolved, dreamlike
Suspended 2 (sus2)	Root – Major 2nd – Perfect 5th	0 – 2 – 7	C–D–G	Open, modern, “floating”
Suspended 4 (sus4)	Root – Perfect 4th – Perfect 5th	0 – 5 – 7	C–F–G	Strong, unresolved, pre-cadential

Major and minor are the two primary tonal colors.

Diminished and augmented triads introduce tension and transition.

Suspended triads replace the 3rd to blur tonality and add movement.

Interval Relationships

Visually or numerically, each triad is constructed by stacking two thirds:

Triad Type	Lower Third	Upper Third	Resulting 5th
Major	Major 3rd	Minor 3rd	Perfect 5th
Minor	Minor 3rd	Major 3rd	Perfect 5th
Diminished	Minor 3rd	Minor 3rd	Diminished 5th
Augmented	Major 3rd	Major 3rd	Augmented 5th

Inversions

A triad can appear in three positions depending on which note is in the bass:

Inversion	Bass Note	Example (C Major)	Symbol	Function
Root Position	Root	C–E–G	C	Most stable form
1st Inversion	3rd	E–G–C	C/E	Softer, smooth voice leading
2nd Inversion	5th	G–C–E	C/G	Suspended, often used for cadences or passing motion

Inversions are critical for voice leading, bass motion, and smooth harmonic transitions in composition and arranging.

Harmonic Function in Context

Triads gain meaning from their position in the scale (the Roman numeral system):

Scale Degree	Triad	Quality in Major	Quality in Minor
I	Tonic	Major	Minor
ii	Supertonic	Minor	Diminished
iii	Mediant	Minor	Major
IV	Subdominant	Major	Minor
V	Dominant	Major	Major
vi	Submediant	Minor	Major
vii°	Leading tone	Diminished	Diminished

The I–IV–V relationship defines major-key harmony, while i–iv–v (or i–♭VI–♭VII) underpins minor-key and modal contexts.

Real-World Examples

Triad Type	Song	Artist	Usage
Major	“Let It Be”	The Beatles	Diatonic I–V–vi–IV progression
Minor	“Creep”	Radiohead	i–III–IV–IV progression in G minor
Diminished	“Because”	The Beatles	Passing tension before resolution
Augmented	“Oh Darling”	The Beatles	Chromatic lift between phrases
Sus4	“Pinball Wizard”	The Who	Power-chord style open suspension

Summary

Attribute	Value
Foundation	Three-note chord built in 3rds
Tonal Color	Determined by 3rd and 5th
Variants	Major, Minor, Diminished, Augmented, Suspended
Key Usage	Tonal harmony building block
Inversions	Root, 1st, 2nd
Function	Establishes harmonic stability, direction, and voice leading