Building Major Scales

Whole steps and half steps

A scale is built from two intervals. That's it.

A half step is the smallest distance between two notes on the keyboard — from one key to the very next key. The next key over might be black or white. Doesn't matter. It's still one half step.

A whole step is two half steps. You skip one key in between.

Above: C to D is a whole step. There's a black key in between them (C♯/D♭), and you're skipping over it.

Above: E to F is a half step. There's no black key between them — they're already as close as two notes can be.

This is the only asymmetry you need to know. The keyboard isn't symmetric — it has two places where the white keys are already a half step apart. That asymmetry is what forces sharps and flats to appear in some keys but not others.

W — W — H — W — W — W — H

Every major scale, no matter what note it starts on, follows the same interval pattern between consecutive notes.

Whole, whole, half — whole, whole, whole, half. That's the rule. The two half steps fall between the 3rd and 4th notes, and between the 7th and 8th.

Start on any note. Apply this pattern. You get a major scale. The starting note names the key.

C major — the free scale

Start on C. Apply the formula.

No sharps. No flats. C major lands on the white keys because the formula's half steps — between 3-4 and 7-8 — line up exactly with the keyboard's natural half steps (E to F, B to C).

C major is the only key where this happens. Every other key requires at least one black key to make the pattern work.

G major — the F♯ moment

Start on G. Apply the formula.

This is the answer to your question from Sunday. The F♯ in G major isn't arbitrary. It isn't "the way it was invented." It's forced by the formula. If you wrote F instead of F♯, you'd have a half step where a whole step is required, and the scale wouldn't be major anymore.

Same logic on the other side: from F♯, a half step lands on G — which is exactly where you need to be to complete the octave. Everything fits because the formula was applied correctly.

F major — the B♭ moment

Start on F. Apply the formula.

Same idea, opposite problem. In G major, the natural half step E→F was too short, so the 7th got pushed up to F♯. In F major, the natural whole step A→B is too long, so the 4th gets pushed down to B♭.

Notice one more thing: F major uses B♭, not A♯. Same key on the piano, different spelling. The rule is that a major scale must use each letter name exactly once — F, G, A, B, C, D, E. If we spelled it A♯, we'd have two A's and no B. The letter-per-position rule forces the flat spelling.

All 12 major scales

Every one of these is built from the same formula. Verify any of them by counting whole and half steps yourself — the formula will check out every time.

Pattern to notice: keys add sharps in a fixed order (F♯, C♯, G♯, D♯, A♯, E♯, B♯), and flats in the reverse order (B♭, E♭, A♭, D♭, G♭, C♭, F♭). This is called the circle of fifths, but you don't need to memorize the circle yet — just know the formula and you can build any scale from scratch.

Scale construction practice

30 questions across all 12 keys. Each one tests whether you can find the right note at a given position in a given key. The answer feedback shows the full scale with the asked position highlighted.