Triads
A triad is a three-note chord built from a root, a third and a fifth. The four basic types are major, minor, diminished and augmented. Build all four from C and hear exactly which notes move. Follow the interactive lesson below to learn more.
Compare four triads from C
Every triad is two thirds stacked on top of each other.
What you just learned
- Two thirds
Every triad is two thirds
C to E is four half steps, E to G is three. Every triad stacks two thirds like this.
C E G = 4 + 3Read the full answer ↓ - Shrink them
Lower the middle, get minor
Move E down to E♭ and the thirds become 3 then 4. C to G stays seven half steps.
C E G → C E♭ GRead the full answer ↓ - Shrink them
Three plus three is diminished
Lower G to G♭ as well. The outside shrinks to six half steps, a tritone that will not sit still.
C E♭ G♭ = 3 + 3Read the full answer ↓ - Stretch them
Four plus four is augmented
Back to C major, then raise G to G♯. Every gap is four, so no note can claim to be the root.
C E G → C E G♯Read the full answer ↓ - Stretch them
Only the inside distances change
Play all four in a row. The outside goes 7, 7, 6, 8, and only the two thirds change.
4+3 · 3+4 · 3+3 · 4+4Read the full answer ↓ - Good to know
A scale gives seven triads
Stack every other note of C major. The qualities run major, minor, minor, major, major, minor, diminished.
C E G · D F A · E G BRead the full answer ↓
Where to go from here
Every part of the lesson, answered in full
Open any question to read the full answer.
What makes a chord a triad?
A triad uses three different letter names arranged as stacked thirds. Start on C, skip D to reach E, then skip F to reach G. C-E-G forms a C major triad.
The notes do not have to remain in that order. E-G-C and G-C-E contain the same three pitch classes and are inversions of C major.
Doubling a note also keeps the triad identity. C-E-G-C uses four sounding notes but only three pitch classes, so its underlying chord is still a C major triad.
What do the root, third and fifth mean?
The root is the reference note and gives the chord its letter name. Every other chord tone is measured from it.
The third can be major or minor. From C, E is four semitones above the root and E flat is three. This difference separates the basic major and minor triads.
The fifth can be perfect, diminished or augmented. G is seven semitones above C, G flat is six and G sharp is eight.
These names describe intervals from the root. They remain root, third and fifth even when a different chord tone is placed in the bass.
How do you build the four triad types?
Keep C as the root:
- C major: C-E-G | 4 then 3 semitones | major third and perfect fifth
- C minor: C-E flat-G | 3 then 4 | minor third and perfect fifth
- C diminished: C-E flat-G flat | 3 then 3 | minor third and diminished fifth
- C augmented: C-E-G sharp | 4 then 4 | major third and augmented fifth
The paired numbers measure the two stacked thirds. The root-to-fifth distances are 7 for major and minor, 6 for diminished and 8 for augmented.
Build them in this order and listen to one change at a time: C major, C minor, C diminished, then back to C major and C augmented.
Why are there four basic combinations?
A diatonic third can be major or minor. Stack two thirds and you have four possible pairings:
- major plus minor
- minor plus major
- minor plus minor
- major plus major
Those pairings produce the four triad qualities. Other spellings are possible in advanced harmony, but these four form the basic tertian system used for tonal chords.
The order matters. Major plus minor gives a major triad; minor plus major gives a minor triad. Both end on a perfect fifth, yet the third above the root changes.
How do the four triads behave?
Major and minor triads both contain a perfect fifth. They can function as stable tonic chords because the outer root-fifth frame remains firm.
A diminished triad narrows the fifth to a tritone. In B-D-F, B often rises to C while F falls to E, leading toward C major.
An augmented triad widens the fifth. C-E-G sharp divides the octave into three equal major thirds, so any note can sound like a possible root. That symmetry makes its direction depend strongly on the following chord.
Describe the note motion before assigning an emotion. Register, instrumentation, rhythm and harmonic function can make the same triad feel very different.
How do triads come from a scale?
Take every other note of the C major scale from each degree:
- C-E-G: C major
- D-F-A: D minor
- E-G-B: E minor
- F-A-C: F major
- G-B-D: G major
- A-C-E: A minor
- B-D-F: B diminished
The quality pattern is major, minor, minor, major, major, minor, diminished. It repeats in every major key because the scale's interval pattern repeats.
This is the bridge between scales and harmony: the scale provides the note collection, and stacked thirds produce its diatonic chords.
What are triad inversions?
Root position places the root in the bass: C-E-G.
First inversion places the third in the bass: E-G-C. Chord symbols can write this as C/E.
Second inversion places the fifth in the bass: G-C-E, written C/G when the bass needs to be explicit.
All three contain C, E and G. The bass changes their weight, spacing and voice-leading possibilities without changing the underlying triad quality.
Are all three-note groups triads?
No. C-D-G contains three pitch classes but is not a standard tertian triad because its basic spelling does not stack thirds. It may be labeled Csus2.
C-F-G can be Csus4. C-G alone with C doubled is a power-chord voicing, not a complete triad, because it contains only two pitch classes and no third.
Calling every three-note sonority a triad hides useful information. A triad specifically names the root-third-fifth structure.
How should you practice triads?
Choose one root and play all four qualities without moving the root. Name the semitone formula before each chord.
Then choose a major scale and build a triad on every degree using only scale notes. Say each quality aloud.
Finally, invert one triad through root position, first inversion and second inversion. Keep naming the root even when it is no longer the lowest note.