What Is a Triad? Building Blocks of Chords
Published February 12, 2026
Learn what triads are, how they are built from stacked thirds, and the four types (major, minor, diminished, augmented). Understand why every chord you hear is built on this simple foundation.
Key Takeaways
- A triad is a three-note chord built by stacking two thirds on a root note.
- Four types: major (happy), minor (sad), diminished (tense), augmented (dreamy).
- Major triad: root + major 3rd + perfect 5th. Minor triad: root + minor 3rd + perfect 5th.
- Inversions change which note is in the bass without changing the chord itself.
- Every major key has the same triad type pattern: I-ii-iii-IV-V-vi-vii°.
What Is a Triad?
A triad is a three-note chord built by stacking two thirds on top of a root note. The three notes are called the root, the third, and the fifth. Triads are the foundation of nearly all Western harmony.
A third is the interval between a note and the note two letter names above it (e.g., C to E is a third, D to F is a third). Thirds can be major (4 semitones) or minor (3 semitones), and this single difference determines whether the triad sounds happy or sad.
The type of triad depends on the combination of thirds: major-major creates a major triad, minor-minor creates a minor triad, major-minor creates a diminished triad, and minor-major creates an augmented triad.
The Four Types of Triads
Major triad: Major third + minor third (root, major 3rd, perfect 5th). Bright, happy, stable. C major = C-E-G. The interval from root to third is 4 semitones, and third to fifth is 3 semitones.
Minor triad: Minor third + major third (root, minor 3rd, perfect 5th). Dark, sad, introspective. C minor = C-Eb-G. Flattening the third by one semitone changes the entire character.
Diminished triad: Minor third + minor third (root, minor 3rd, diminished 5th). Tense, unstable, dissonant. B diminished = B-D-F. The flat fifth adds extra tension beyond the minor third.
Augmented triad: Major third + major third (root, major 3rd, augmented 5th). Mysterious, unsettled, dreamlike. C augmented = C-E-G#. The raised fifth creates a symmetrical, floating quality.
Triads and Inversions
Root position: The root is the lowest note (C-E-G). This is the most stable voicing of the triad.
First inversion: The third is the lowest note (E-G-C). This sounds lighter and less grounded. The interval from the bass to the top note becomes a sixth.
Second inversion: The fifth is the lowest note (G-C-E). This sounds the most unstable and is often used as a passing chord or in cadences.
Inversions let you create smooth bass lines and voice leading without changing the underlying chord. A I-V-vi-IV progression in C (C-G-Am-F) sounds more connected when you choose inversions that move the bass by step.
Practice Exercises
- 1Build all four triad types on C: C major (C-E-G), C minor (C-Eb-G), C diminished (C-Eb-Gb), C augmented (C-E-G#). Play each and notice the mood difference.
- 2On guitar, play the three-string triad shapes for C major in root position, first inversion, and second inversion on the G-B-E strings.
- 3In the key of G major, identify the triad built on each scale degree. Play I-IV-V-I using triads only.
Common Mistakes
- Confusing the types by forgetting the order of thirds. Remember: major = major+minor, minor = minor+major, diminished = minor+minor, augmented = major+major.
- Always playing root position triads. Practice inversions to create smoother voice leading and more musical chord progressions.
- Thinking triads are only for beginners. Professional musicians use triads extensively — they are simpler than extended chords but far from basic.
Frequently Asked Questions
What is the difference between a triad and a chord?
A triad is a specific type of chord with exactly three notes. All triads are chords, but many chords have more than three notes (seventh chords, extended chords, etc.). Triads are the building blocks from which more complex chords are constructed.
How do I build a major triad?
Take a root note, count up 4 semitones (major third) for the third, then 3 more semitones (minor third) for the fifth. For C major: C + 4 semitones = E, E + 3 semitones = G. Result: C-E-G.
Why is the diminished triad unstable?
The diminished triad contains a diminished fifth (tritone) between the root and the fifth. The tritone is the most dissonant interval in Western music, creating a strong pull toward resolution. This is why diminished chords almost always resolve to a more stable chord.
Can I play triads on guitar?
Yes, and you should. Triads on guitar are typically played on three adjacent strings (treble, middle, or bass groups). They are lighter and more versatile than full barre chords and are essential for funk, R&B, and progressive rock.
What triad types appear in a major key?
In any major key: I is major, ii is minor, iii is minor, IV is major, V is major, vi is minor, and vii° is diminished. This pattern always holds regardless of the key.