Triads

The four shapes, and what separates them

Two intervals decide everything. Stack a major third then a minor one and you get major (C E G). Reverse them and you get minor (C E♭ G). Stack two minor thirds and you get diminished (C E♭ G♭); two major thirds gives augmented (C E G♯).

Major and minor keep a perfect fifth on the outside, which is why they sound settled. Diminished and augmented do not, and that missing anchor is the whole reason they behave as passing chords rather than destinations.

Triads on the guitar: five shapes, one system

This is the most searched question about the group, and the useful answer is not a chart of 48 shapes. Open C (x32010), A (x02220), G (320003), E (022100) and D (xx0232) can each be barred and moved, so five hand positions cover every major triad on the neck. That is the CAGED system, and it exists precisely because triads repeat.

Minor versions come from the same five by lowering one note. Am is x02210 — the open A with one finger lifted. Once you see that the third is the only note that moves, the fretboard stops being a table to memorise.

Three-string triads

Players who move past open chords usually learn triads again on three adjacent strings. The same three notes, played high on the neck, cut through a mix where a six-string chord turns to mud, and they leave room for a bass player.

There are three arrangements of any triad — root position, first inversion, second inversion — and on three strings each is one small shape. Nine shapes per string group, and you can comp through an entire song without a barre.

Where each one lives in a key

Build a triad on every degree of the major scale and the pattern is fixed: major on I, IV and V; minor on ii, iii and vi; diminished on vii. Augmented does not occur in the natural major scale at all — it needs harmonic minor or a deliberate alteration.

This is why three chords carry so much popular music. I, IV and V are the major ones, and the vi gives you the relative minor without changing a single key signature.

On the piano

The interval count works identically: four semitones then three for major, three then four for minor. What changes is that the piano shows you inversions physically — the same three keys, a different one at the bottom.

Practising triads through inversions is worth more than practising them in root position through all twelve keys. Real accompaniment moves by the smallest distance available, and that distance is almost always an inversion away.

Frequently asked questions