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How Triads Are Built

Theory8 minScale degrees · how triads are built · seventh chords

You don't have to memorize chords — they're stacked up layer by layer in “thirds.” Once you understand how they're built, you can work out any chord yourself.

Video lessons are in production — follow the notes and practice checklist below and you'll learn it just fine.
Stage 6 · Chords & Theory, Deeper8 lessons

You're on lesson 2 / 8 in this stage

Show all 8 lessons
  1. Scale Degrees & Chord Function9 min
  2. How Triads Are Built8 min
  3. Intro to Seventh Chords9 min
  4. Intervals: Number & Quality9 min
  5. Secondary Dominants & Cadences9 min
  6. Putting the Circle of Fifths to Work8 min
  7. Inversions & Slash Chords: Get the Bass Line Moving9 min
  8. The Four Magic Progressions in Practice9 min

Stacking thirds

Start from a root note and stack two “thirds” on top, and you've built a triad: root + 3rd + 5th.

There are two kinds of third: a major third = 4 semitones (4 frets), a minor third = 3 semitones (3 frets). Stack them in a different order and the chord takes on a different color.

Major chord vs. minor chord

Major third + minor third = a major triad, bright (like C = C–E–G); minor third + major third = a minor triad, soft and dark (like Dm = D–F–A).

The only difference is in that bottom third — which is exactly why C and Cm differ by just the middle note.

Proving it once on the fretboard with your own hands beats reading about it ten times: hold Am, and lift the finger on the 2nd string 1st fret up to the 2nd fret — now it's A (the ♭3 raised back to 3); hold E, and release the 3rd string 1st fret to an open string — now it's Em (the 3 lowered to ♭3). One finger, one semitone, is the entire distance between “bright” and “sad.” Play it and listen.

  • 💡 Remember this rule and you can work out the major or minor chord from any note, instead of memorizing a chord chart.

How C's six common chords are built

On the C major scale, take “every other note, three notes in all”: C=1·3·5, Dm=2·4·6, Em=3·5·7, F=4·6·1, G=5·7·2, Am=6·1·3 — exactly the degrees 1–6 from the last lesson.

Chords in this lesson

Tap the 🔊 under each diagram to match every chord's sound to its shape.

✕321
✕✕231
23
1342
213
✕231
⏱️ Cycle this lesson's chords to a beatPractice switching without stopping (one-minute changes) — first learn each chord by ear and shape, then drill clean changes between them.Expand

Switch back and forth between this lesson's chords to the beat below.

Tap “Start” to play along with the beat
CDmEmFGAm
Speed80 BPM
Time

One bar of count-in first, then the chord changes automatically each bar. Get it smooth slowly, then speed up bit by bit.

Want to count how many changes you can do in 60 seconds? Head to the one-minute changes drill.

Go play these

Songs that fit this lesson's technique and chords — pick one and practice in the library:

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Practice checklist

  • Write out the three notes that make up the G chord and the Am chord.
  • Say which note you lower by a semitone to turn C into Cm.