HearmonyWhat Is a Triad? Major, Minor, Diminished and Augmented Triads
A triad is a three-note chord built by stacking two thirds: a root, a third above it and a fifth above the root. C–E–G is a C major triad. There are four kinds of triad, major, minor, diminished and augmented, and the only thing that separates them is the size of those two thirds.
Below you will find all four types spelled on every natural root, the triads that live in a major and a minor key, and a short routine for telling them apart by ear.
What is a triad in music?
A triad in music is a chord of three notes, each a third apart, named after its lowest stacked note, the root. Take any note, skip one letter, take the next, skip one, take the next: C (skip D) E (skip F) G. That "every other letter" rule is why a triad always uses three letters a third apart, whatever sharps or flats it needs.
The three notes have fixed names:
- Root: the note the chord is named after (C in C major).
- Third: three letters up (E). It decides whether the chord sounds major or minor.
- Fifth: five letters up (G). It decides whether the chord sounds stable or not.
Almost every chord you meet in pop, folk, rock and classical music is a triad or a triad with extra notes on top. A seventh chord, for example, is a triad plus one more third. The Wikipedia entry on triads covers the history of the term.
What are the 4 types of triads?
The four types of triads are major, minor, diminished and augmented. Each one combines a major third (4 semitones) and a minor third (3 semitones) in a different order, or doubles one of them.
| Triad | Notes on C | Thirds, bottom to top | Semitones | Fifth | Symbol |
|---|---|---|---|---|---|
| Major | C E G | major + minor | 4 + 3 | perfect | C |
| Minor | C E♭ G | minor + major | 3 + 4 | perfect | Cm |
| Diminished | C E♭ G♭ | minor + minor | 3 + 3 | diminished | Cdim, C° |
| Augmented | C E G♯ | major + major | 4 + 4 | augmented | Caug, C+ |
Major and minor share the same perfect fifth (7 semitones) and swap only the third, which is why they are the pair most beginners learn first; the guide to major vs minor chords goes deep on that one note. Diminished squeezes the fifth down a half step, and augmented stretches it up a half step.
Every triad on every natural root
Here are all four triad types on the seven natural notes, spelled correctly. Keep the letters a third apart: D augmented is D F♯ A♯, never D G♭ B♭.
| Root | Major | Minor | Diminished | Augmented |
|---|---|---|---|---|
| C | C E G | C E♭ G | C E♭ G♭ | C E G♯ |
| D | D F♯ A | D F A | D F A♭ | D F♯ A♯ |
| E | E G♯ B | E G B | E G B♭ | E G♯ B♯ |
| F | F A C | F A♭ C | F A♭ C♭ | F A C♯ |
| G | G B D | G B♭ D | G B♭ D♭ | G B D♯ |
| A | A C♯ E | A C E | A C E♭ | A C♯ E♯ |
| B | B D♯ F♯ | B D F♯ | B D F | B D♯ F𝄪 |
A few spellings look strange but follow the rule: E augmented ends on B♯ (the same key as C), F diminished ends on C♭ (the same key as B), and B augmented needs F𝄪, F double sharp, which you play as G.
Which triads are in a major key?
A major key contains three major triads, three minor triads and one diminished triad, always in the same order. Build a triad on each note of the C major scale, using only white keys, and you get this pattern:
| Degree | Numeral | Chord in C major | Notes | Type |
|---|---|---|---|---|
| 1 | I | C | C E G | major |
| 2 | ii | Dm | D F A | minor |
| 3 | iii | Em | E G B | minor |
| 4 | IV | F | F A C | major |
| 5 | V | G | G B D | major |
| 6 | vi | Am | A C E | minor |
| 7 | vii° | B° | B D F | diminished |
Uppercase numerals mean major, lowercase mean minor, and the small circle means diminished. The pattern major, minor, minor, major, major, minor, diminished is the same in all twelve major keys, so in G major the chords are G, Am, Bm, C, D, Em and F♯°.
Minor keys shuffle the same pattern. In A minor (natural minor) the triads are Am, B°, C, Dm, Em, F and G (i, ii°, III, iv, v, VI, VII). Raise the seventh note to G♯, as most minor-key music does, and v becomes a major E chord (E G♯ B), which pulls much harder to Am. The same G♯ turns III into C augmented (C E G♯), the one place an augmented triad grows naturally inside a key. More on that chord in the guide to the augmented chord.
Root position and inversions
A triad is in root position when the root is the lowest note, and in an inversion when the third or fifth is at the bottom. C major can be played C–E–G (root position), E–G–C (first inversion) or G–C–E (second inversion). All three are still C major, and the quality does not change.
Inversions smooth out the movement between chords and change the bass line. Slash-chord symbols such as C/E, figured-bass names and the sound of each inversion are covered in chord inversions explained.
How to tell triads apart by ear
To tell triads apart by ear, ask two questions in order: is the chord stable, and is it bright or dark? Major and minor can end a song; diminished and augmented cannot.
- Stable or restless? If the chord could be the last chord of a song, it is major or minor. If it sounds like it needs to move on, it is diminished or augmented.
- Stable and bright: major. Stable and dark: minor.
- Restless and squeezed, dark: diminished. Restless and stretched, floating: augmented.
- Still unsure? Play the chord one note at a time, low to high. Small step then large step (3 + 4) is minor; large then small (4 + 3) is major; two small steps is diminished; two large steps is augmented.
Common mistakes and how to fix them
- Calling diminished "minor". Both have the dark minor third on the bottom. Fix: ask whether it could end the song. If not, it is diminished. The diminished chord guide has a drill for exactly this pair.
- Calling augmented "major". Both start with a bright major third. Fix: listen to the top note. In augmented it sounds like it wants to rise.
- Spelling by key instead of letter. The black key between G and A is G♯ in C augmented but A♭ in F minor. Count letters first, then add the sharp or flat.
A five-day plan (five minutes a day)
- Day 1: C major vs C minor, ten rounds with your eyes closed.
- Day 2: Add C diminished. Play the three in random order and name each one.
- Day 3: Add C augmented. Compare it with C major first, then mix all four.
- Day 4: All four types on D, F and G. Use the spelling table to check yourself.
- Day 5: Play the seven triads of C major (C, Dm, Em, F, G, Am, B°) in random order and name each type.
Self-test: name the type. G B D · F A♭ C · E G♯ B♯ · B D F · A C E · D F♯ A. Answers: major, minor, augmented, diminished, minor, major.
Practice triads in Hearmony
Hearmony's Chord Garden adventure trains the four triad types one pair at a time. The "Happy and sad" unit starts with major vs minor, "Spooky chords" adds diminished, "Dreamy chords" adds augmented, and the Garden mix combines them with sus chords and odd-one-out questions. In the early lessons each chord is played note by note before it sounds together, so you can hear the thirds stack up; later the chords come as one block, the way they appear in music. The Seventh Heaven adventure then asks for the same four types in inversions.
The free Chord Numbers side quest covers the triads of a key: what I, IV and V mean, why ii, iii and vi are minor, and how to hear the numbers in a short progression. Chord Garden is part of Hearmony Pro, while the first adventure and the side quests are free. To see where chords fit into a full routine, start with ear training exercises for beginners.