Building Triads from the Major Scale

A triad is the simplest possible chord: just three notes. Every major and minor chord shape you've learned so far is, underneath the extra doubled notes a guitar chord shape usually includes, built from a triad. This tutorial shows where those three notes come from, and why a major scale naturally produces a specific mix of major and minor chords.

What you'll need

• A major scale you can play (see the "Major Scale Positions" tutorial), C major is used as the example here
• Basic interval knowledge is helpful but not required

Steps

1. Learn the stacking rule. A triad is built by taking a note from a scale, then skipping one note, then skipping one more — in scale-degree terms, the 1st, 3rd, and 5th notes of a scale, starting from wherever you choose. This "every other note" pattern is called "tertian" harmony, and it's the basis of nearly all Western chord construction.

2. Build the C major triad. Starting on C in the C major scale (C-D-E-F-G-A-B), take the 1st (C), 3rd (E), and 5th (G) notes. Play those three notes together — that's a C major chord, in its simplest three-note form.

3. Build the triad starting on D, the 2nd scale degree. Taking every-other note starting from D gives you D, F, A. Play those three together, and you'll hear it sounds noticeably different from the C triad — darker, more minor. This happens automatically because of where the scale's half-steps (E-F and B-C) fall relative to this new starting point, not because you changed anything about the method.

4. Build a triad from every note of the scale, one at a time, and notice the resulting pattern of chord qualities: major, minor, minor, major, major, minor, diminished — for the 1st through 7th scale degrees respectively, in any major key. This major-minor-minor-major-major-minor-diminished pattern is identical in every major key, not just C.

5. Connect this to Roman numeral chord analysis. Musicians label these seven triads with Roman numerals — uppercase for major, lowercase for minor: I, ii, iii, IV, V, vi, vii°. A huge number of pop and rock progressions, like the I-V-vi-IV progression, are really just describing which of these seven scale-built chords are being used, and in what order.

6. Apply it to a key you already play in. In the key of G major, work out the seven triads (G, Am, Bm, C, D, Em, F#dim) using the same 1st-3rd-5th method, and check a few against open chord shapes you already know — you'll likely recognize G, Am, C, D, and Em as chords you already play regularly together.