A chord triad is a three-note chord built by stacking two 3rds on top of a root note. The four types are major (root, major 3rd, perfect 5th), minor (root, minor 3rd, perfect 5th), diminished (root, minor 3rd, diminished 5th) and augmented (root, major 3rd, augmented 5th).
What is a chord triad?
A triad is the simplest complete chord in Western music: three notes, stacked in 3rds, that together define a harmony. The word comes from the Latin for three, and the idea is older than the piano, the guitar and most of the music we play today. Every larger chord, from a dominant 7th to a 13th, is a triad with extra notes piled on top, so understanding triads means understanding the foundation of nearly all harmony. Triads are built by taking a scale and picking every other note. In C major, the scale is C, D, E, F, G, A, B, and taking the 1st, 3rd and 5th notes gives C, E and G, the C major triad. Move the starting point to D and the same skipping pattern gives D, F and A, the D minor triad. This skipping pattern is the single most useful idea in chord theory, because it explains why some chords in a key are major and some are minor: the pattern is the same, but the notes it lands on are different.
How triads are built
There are four triad types, and each is defined by the size of its two 3rds. A major triad stacks a major 3rd (four semitones) and then a minor 3rd (three semitones): C to E is four semitones, E to G is three, and the outer notes C to G span seven semitones, a perfect 5th. A minor triad reverses the order: a minor 3rd first, then a major 3rd. A to C is three semitones, C to E is four, and the outer notes still span a perfect 5th. A diminished triad stacks two minor 3rds: C to Eb is three semitones and Eb to Gb is three more, so the outer notes span only six semitones, a diminished 5th, which is why the chord sounds tense and unstable. An augmented triad stacks two major 3rds: C to E is four semitones and E to G# is four more, so the outer notes span eight semitones, an augmented 5th, which gives the chord its floating, unresolved quality. The C major guitar chord, the A minor guitar chord and the B diminished guitar chord show three of the four types side by side.
Worked example — triads in G major. The G major scale is G, A, B, C, D, E, F#. Skipping every other note from G gives G, B, D: a major triad, because G to B is four semitones. From A it gives A, C, E: a minor triad, because A to C is three semitones. From B it gives B, D, F#: minor again. From F# it gives F#, A, C: a diminished triad, because F# to A is three semitones and A to C is three more. That is the whole diatonic set for G major: three major triads, three minor triads and one diminished triad. Check the pattern against the key of G major and the G major scale, or build any triad with the chord finder.
How to practise triads
Triad practice is mostly a thinking exercise: if you can name the notes, your hands will follow. Work through one key a day until the pattern is automatic.
- Pick a key, write out its scale, then build the triad on each of its seven degrees by skipping every other note, naming the quality of each triad as you go.
- On piano, play the C major triad C–E–G in root position, then play it as an arpeggio, one note at a time, ascending and descending.
- On guitar, find the G major guitar chord triad on the top three strings only, then move the same shape up two frets and identify the new chord.
- Play the three minor triads of the key of C major — Dm, Em and Am — and listen for the darker sound that the minor 3rd creates.
- Use the scale degree calculator to check which degree of a scale a note belongs to when you are unsure.
Common mistakes
- Thinking a triad is any three notes — Three random notes are not a triad. A triad is specifically a root with two stacked 3rds, which means the notes must be a 3rd apart in letter names: C–E–G, never C–D–G or C–E–A.
- Confusing the diminished triad with a minor triad — A minor triad has a perfect 5th, seven semitones above the root, while a diminished triad has a diminished 5th, six semitones above the root. That one semitone is the whole difference, and it changes the chord from stable to unstable.
- Forgetting that triads can be inverted — C–E–G, E–G–C and G–C–E are all the same triad in different inversions. Beginners sometimes think E–G–C is a different chord, but the notes are identical, only the lowest note has changed.
Quick reference
The four triad types are easiest to compare on the same root, because then only the intervals change and the root stays still. This table works them all out on C, so you can see at a glance how the major triad differs from the minor triad, and how the diminished and augmented triads stretch or squeeze the same three notes.
| Triad type | Notes on C | Intervals (semitones) |
|---|---|---|
| Major | C – E – G | 0, 4, 7 |
| Minor | C – D# – G | 0, 3, 7 |
| Diminished | C – D# – F# | 0, 3, 6 |
| Augmented | C – E – G# | 0, 4, 8 |
Practise the table by building each triad on a different root, starting with G, and check that the interval pattern from the third column still holds. When you can name the notes of all four triad types on any root without hesitating, you have the foundation that every larger chord is built on.
Frequently asked questions
What is a triad in music?
A triad is a three-note chord made by stacking two 3rds above a root note. The four types are major, minor, diminished and augmented, and they are defined by whether each 3rd is major or minor. Almost every chord in popular music is a triad or a triad with extra notes added.
How many triads are there in a major key?
Seven, one on each degree of the scale. In C major they are C, Dm, Em, F, G, Am and Bdim: three major, three minor and one diminished. The same pattern, three major, three minor and one diminished, holds in every major key.
What is the difference between a triad and a chord?
A triad is a specific kind of chord, the three-note kind. All triads are chords, but not all chords are triads: a 7th chord has four notes, a 9th chord has five, and a power chord has only two. The triad is the simplest complete chord.
Are triads used in real songs?
Constantly. Most pop, rock, folk and country songs are built almost entirely from triads, with 7th chords used as decoration. If you can play the triads of a key, you can play the harmony of most songs in that key.
Can a triad have more than three notes?
No. The moment you add a fourth distinct note, such as a 7th, the chord is no longer a triad. You can double the existing notes across octaves, so a piano chord with six notes can still be a triad, but it still contains only three distinct pitches.