Pitch, the Major Scale & Key Signatures

You’ll be able to

Name pitches and identify half steps and whole steps between them
Construct any major scale using the whole-and-half-step pattern
Determine a major key signature and place it on the circle of fifths

Pitch, letter names, and the two step sizes

Pitches cycle through seven letter names — A B C D E F G — and then repeat an octave higher. Accidentals raise or lower a letter: a sharp (♯) raises a pitch one half step, a flat (♭) lowers it one half step, and a natural (♮) cancels either. The smallest distance in Western music is the half step (adjacent keys on a piano, e.g. E to F). Two half steps make a whole step (e.g. C to D). Crucially, the natural half steps fall between E–F and B–C; every other pair of adjacent letters is a whole step. Two spellings for the same sound (e.g. F♯ and G♭) are enharmonic equivalents.

Building the major scale

A major scale is seven pitches spanning an octave, built from a fixed pattern of whole (W) and half (H) steps: W–W–H–W–W–W–H. Starting on C uses only white keys — C D E F G A B C — because the natural half steps (E–F, B–C) already land in the right places. Start anywhere else and you must add sharps or flats to preserve the pattern. Each degree has a name and a solfège syllable: do (tonic), re (supertonic), mi (mediant), fa (subdominant), sol (dominant), la (submediant), ti (leading tone), do.

Key signatures and the circle of fifths

Rather than write accidentals repeatedly, a key signature collects them at the start of the staff. Sharps always appear in the order F C G D A E B; flats appear in the reverse order B E A D G C F. The circle of fifths organizes the keys: moving up a perfect fifth adds one sharp (C → G → D → A → E → B), and moving down a fifth adds one flat (C → F → B♭ → E♭ → A♭). Two shortcuts: the last sharp in a signature is ti (a half step below the tonic), and the second-to-last flat names the major key.

Major scale step pattern

W – W – H – W – W – W – H (do re mi fa sol la ti do)

Half steps fall between degrees 3–4 (mi–fa) and 7–8 (ti–do). Every major scale, in any key, uses exactly this pattern.

Worked example

Build the A major scale and state its key signature.

1.Start on A and apply W–W–H–W–W–W–H, spelling one of each letter A B C D E F G.
2.A to B is a whole step (B). B up a whole step is C♯ (C to C♯). C♯ up a half step is D. D up a whole step is E. E up a whole step is F♯. F♯ up a whole step is G♯. G♯ up a half step is A.
3.The scale is A – B – C♯ – D – E – F♯ – G♯ – A, which requires three sharps.
4.Taken in sharp order (F C G D A E B), the first three are F♯, C♯, G♯ — exactly the altered notes.

Answer: A major = A B C♯ D E F♯ G♯ A, with a key signature of three sharps: F♯, C♯, and G♯.

Checkpoint

Between which pair of natural (unaltered) pitches is there a half step?

Watch out

A major scale must use each letter name exactly once. Spell the D major scale as D E F♯ G A B C♯ — not D E G♭ G A B D♭ — even though G♭ sounds like F♯. Repeating or skipping a letter (a "spelling error") is a common mistake that also makes the key signature impossible to read.

Checkpoint

Which major key has a key signature of exactly two sharps, F♯ and C♯?

On the exam

To name a sharp key fast, take the last sharp and go up a half step — that is the tonic (last sharp C♯ → tonic D). For flat keys, the second-to-last flat is the tonic (flats B♭ E♭ A♭ → tonic E♭). Memorizing these two tricks saves time on the exam.

Answer the 2 checkpoints as you read.