Triads: three notes, two thirds
A triad is the simplest chord: a root, then a third above it, then a fifth above that. Count in letters (C, E, G: every other letter) and in half steps. There are two sizes of third, and the way you combine them gives the four triads.
- Major: major third (4 half steps) + minor third (3). C E G.
- Minor: minor third (3) + major third (4). C E♭ G.
- Diminished: minor third + minor third. C E♭ G♭.
- Augmented: major third + major third. C E G♯.
| Chord | Formula | Notes on C | Sounds |
|---|---|---|---|
| Cmajor | 1 3 5 | C E G | bright and settled |
| Cmminor | 1 ♭3 5 | C E♭ G | darker and more serious |
| C°diminished | 1 ♭3 ♭5 | C E♭ G♭ | tense, unstable, a little spooky |
| C+augmented | 1 3 ♯5 | C E G♯ | dreamy and restless, with no clear home |
Change one note
The quickest way to remember them: start with a major triad and move one note. Lower the third for minor. Lower the third and the fifth for diminished. Raise the fifth for augmented.
Inversions
A triad can have any of its three notes in the bass. C E G is root position, E G C is first inversion and G C E is second inversion. The chord is still C major. The heavy lift level shows triads in inversions, so you have to find the root first.
How to practise
- Warm-up: major and minor on white-key roots, with note names on the keys.
- Working set: every root, with diminished and augmented joining in. You build chords too.
- Heavy lift: all four in inversions.
Triads are built from intervals. Next, see augmented and diminished chords in depth, practise inversions, or see which triads belong in a key with Roman numerals. Shapes are in the guitar and ukulele chord libraries.
Frequently asked questions
What is a triad?
A chord of three notes built by stacking two thirds: the root, a third above it and a fifth above it. C major is C, E, G.
What are the four types of triad?
Major (major third + minor third), minor (minor third + major third), diminished (minor third + minor third) and augmented (major third + major third).
How do I turn a major triad into a minor triad?
Lower the third by a half step. C major is C E G; C minor is C E♭ G. The root and fifth stay the same.
How can I tell major from minor by ear?
Major sounds bright and settled; minor sounds darker and more serious. Both have a perfect fifth, so they feel equally stable, and only the middle note changes.
What is an inversion?
The same notes with a different one in the bass. C E G is root position; E G C is first inversion; G C E is second inversion. The chord keeps its name.
Which triads are in a major key?
Three major (I, IV, V), three minor (ii, iii, vi) and one diminished (vii°). The augmented triad is not in the major scale.