Harmony Gym

The Major Chord

If you’ve ever heard a song end on a big, satisfied, “everything is resolved” sound — that was almost certainly a major chord. It’s the most common chord in Western music, and once you can build one from any starting note, you’ve unlocked the pattern behind thousands of songs.

What is a chord?

A chord is simply three or more notes played at the same time. The most basic kind of chord is the triad: exactly three notes, built by stacking intervals on top of a starting note called the root. The root gives the chord its name — a chord built on C is “C something”, a chord built on G is “G something”.

The recipe for a major triad

Every major chord follows the same recipe, no matter which note you start on:

  1. Root — pick any note. Let’s use C.
  2. Major third — count 4 semitones up from the root. From C: C♯, D, D♯, E.
  3. Perfect fifth — count 7 semitones up from the root. From C: that lands on G.

So C major = C, E, G. That 4-then-7 pattern is the major chord. Start on G and apply the same counting and you get G major: G, B, D. Start on F♯ and you get F♯ major: F♯, A♯, C♯. The recipe never changes; only the starting note does.

Why it sounds “happy”

The character of a chord comes almost entirely from the interval between the root and the third. A distance of 4 semitones — the major third — produces a bright, open, stable sound that most listeners describe as happy or confident. (In the next lesson you’ll shrink that interval by one semitone and hear how dramatically the mood changes.)

The fifth, sitting 7 semitones above the root, acts more like a frame: it adds fullness and stability but doesn’t change the chord’s emotional color.

Common mistakes to avoid

  • Counting the starting note as “1”. The root is zero. C up to E is 4 semitones (C♯, D, D♯, E), not 5.
  • Confusing the third with “the third white key”. On a keyboard, thirds sometimes cross black keys. Count semitones, not key colors.
  • Building from the wrong root. In this game, the chord is named by its root — if the challenge says “E major”, your lowest conceptual starting point for counting is E, even though you may recognize the shape by eye eventually.

Now play

The exercise below asks you to build major triads starting from all twelve possible roots. Count semitones at first — 4 up, then 3 more (which totals 7 from the root). After a few rounds you’ll start recognizing the shapes on the keyboard, and eventually the sound alone will tell you whether you got it right. That’s the goal: recipe first, then shape, then ear.