How the Major Scale Is Built

This unit is about scales. A scale is the set of notes you get by starting somewhere and selecting pitches according to a fixed sequence of intervals.

The measuring tools from Unit 1 go straight into the definition, because a scale is a pattern of intervals — nothing more.

The major scale is defined by an interval sequence

The major scale is the one whose adjacent notes are spaced like this:

whole – whole – half – whole – whole – whole – half

A whole step is two half steps. Adding them up gives 2+2+1+2+2+2+1 = 12 half steps, which is exactly one octave.

C major looks like the privileged case because it is the only major scale playable entirely on white keys. There is no black key between E and F or between B and C, so running up the white keys from C produces whole-whole-half-whole-whole-whole-half for free.

That is not a coincidence — the keyboard was laid out with C major as its reference. Read the other way around: C major is simple because of how notation and keyboards were designed, not because there is anything musically special about it.

Where the half steps fall decides everything

The character of the major scale comes down to the placement of its two half steps.

Location	Interval	What it does
Degrees 3–4	half step	pins the third degree at a major 3rd from the tonic
Degrees 7–8	half step	creates the strong pull from degree 7 into the tonic

The 7–8 half step is the consequential one. With only a half step left to travel, degree 7 develops a powerful urge to complete the climb. That note is the leading tone, and it becomes the engine behind a great deal of the harmony in later units.

The other half step, between 3 and 4, fixes the third degree at a major 3rd above the tonic. Since the previous unit established that the major/minor third distinction is what sets bright against dark, that half-step placement is what makes the major scale sound major.

Hearing where the half steps are

▶Major scale▶Seventh degree removed▶Third degree lowered

Check: The first is the plain ascending major scale. The second removes the seventh degree and jumps to the tonic, which noticeably weakens the sense of arrival. The third lowers the third degree by a half step, and that single change is enough to stop it being a major scale at all.

W W H W W W H

Check

Is the gap between the fourth and fifth degrees of a major scale a whole step or a half step?

Whole stepHalf stepIt varies by scaleAugmented 2nd

Check answer

The pattern moves

Because the definition is a sequence of intervals rather than a list of notes, you can start it anywhere. Change the tonic, keep the whole-whole-half-whole-whole-whole-half, and the major quality survives intact.

Try building it on D. D–E is a whole step, but E–F is a half step, which breaks the pattern. The third degree has to be two whole steps — four half steps — above the tonic, so F is raised to F♯. Continuing the same way, the seventh degree turns out to need C♯.

That is what a key signature actually is. The previous unit described it as a declaration of which notes are altered; more precisely, it is the list of alterations required to preserve the major scale pattern from a given starting note.

The spelling principle applies here too. The third degree must not be written as G♭, because the degree has to be a kind of F — F♯ and G♭ are the same key but different degrees. Honoring that constraint is what guarantees a major scale always takes seven different letters.

The same pattern at different heights

▶C major▶D major▶A-flat major

Check: All three are whole-whole-half-whole-whole-whole-half. Only the starting note differs. Notice that you recognize all three as the same bright scale despite the difference in pitch — that recognition is the evidence that a scale is a pattern.

Check

What is the third degree of E major?

GG#AbF#

Check answer

Reading the scale as intervals from the tonic

Adjacent intervals are the definition, but for practical work it is more useful to read a scale as intervals measured from the tonic.

Degree	Interval from tonic	Half steps
1	perfect unison	0
2	major 2nd	2
3	major 3rd	4
4	perfect 4th	5
5	perfect 5th	7
6	major 6th	9
7	major 7th	11

This table is what the previous unit meant by saying the major scale supplies the reference sizes for intervals. Knowing the major scale removes any need to memorize the interval reference table — the two are the same information.

This view pays off when chords arrive. As the next unit shows, chords are built by stacking every other note of the scale. Take degrees 1, 3, and 5 and you have the tonic chord; take 5, 7, and 2 and you have the dominant. The scale is the parts list for the chords.

▶ Play D major in the scale dictionary Watch which black keys it uses. Only F♯ and C♯ — two alterations are all it takes to reproduce the C major shape starting from D Scale Dictionary → ▶ Locate major keys on the circle of fifths Each step clockwise adds one sharp, which is to say it adds one more alteration needed to hold the major pattern together Circle of Fifths →

The next lesson asks what happens if you lower the third, sixth, and seventh degrees of this scale. Three different minor scales come out of that question.