Why fifteen keys, not twelve?

The next few steps will teach you a single formula that produces any major scale from any starting note. There are twelve distinct starting notes on a keyboard — one for each note in the octave — so the formula can produce twelve distinct-sounding major scales.

But musicians don’t just write about sound — they write notes on a page. On paper, some of those twelve sounds can be spelled two different ways, because sharps and flats give every black key two names. That is why the practical list of major keys is fifteen, not twelve: the twelve distinct pitches, plus three pairs where two spellings exist for the same sound.

Selecting 7 from 12: what makes a major scale

A major "scale" is a sequence of eight notes, starting and ending on the same letter name an octave apart. But not just any eight notes — the gaps between them must follow a precise pattern to produce the sound we recognise as major.

That pattern is seven steps in a specific order of tones (T) and semitones (S):

T   T   S   T   T   T   S

Apply this sequence starting from any note and you get a major scale starting on that note — complete with all the correct sharps or flats. The "key signature" (the sharps or flats printed at the start of a piece of music) is simply the printed record of which notes had to be adjusted to maintain this pattern from a given starting note.

Now build it yourself

You have just seen the recipe. Set each gap to a Tone (T) or Semitone (S) to build a major scale. Hit Play any time to hear your version — a wrong shape will sound wrong — then Check. Switch the starting note and notice the shape never changes.

One pattern. Twelve keys.

The major scale is not twelve separate things to learn. It is one rigid pattern of steps — tone, tone, semitone, tone, tone, tone, semitone — that can start anywhere. Tap any key below to move the tonic and watch the pattern slide across without changing shape. Whatever keys it lands on, those are the notes of that scale. Key signatures are simply the black keys the pattern is forced to catch.

C major — the pattern on white keys

C major is the only major scale that lands entirely on white keys. The gaps between adjacent white keys happen to follow T-T-S-T-T-T-S exactly, which is why it needs no sharps or flats.

C major on the keyboard

T = tone (two semitones)   S = semitone (one step)

G major — where the sharp comes from

Now apply T-T-S-T-T-T-S starting on G. The first six steps land correctly on G A B C D E. The seventh step demands a tone above E — but a tone above E lands on F♯, not F natural (because E to F is only a semitone, and we need a tone). The pattern forces F♯. That is why G major has one sharp in its key signature.

G major on the keyboard

The blue black key is F♯ — sharpened because the pattern required a tone, not a semitone, at that step.

The tonic — a name worth having

The starting note of a scale has a proper name: the "tonic". In G major the tonic is G. In F major it is F. The tonic is the note the key is named after, and it is the note that feels like home — the note a piece in that key tends to settle on at the end.

Think in numbers, not letters

Here is a mental shift that quietly unlocks a great deal later. Instead of thinking of a scale as the letters C D E F G A B, think of it as positions 1 2 3 4 5 6 7 — the "scale degrees". The tonic is degree 1, the next note up is degree 2, and so on, up to 7, after which you arrive back at 1 an octave higher.

Why bother, when the letters work perfectly well? Because music is relational. The same tune played in C major or in G major uses completely different letters, but exactly the same degrees. A folk song that goes 1–1–5–5–6–6–5 is that same shape whether you start on C or on E♭. The numbers describe what the music is actually doing; the letters are just the particular spelling forced on it by the key you happen to be in.

This is the difference between memorising and understanding. If you learn a piece as “C, then F, then G,” that knowledge is locked to one key. If you learn it as “1, then 4, then 5,” you understand its structure — and you can move it to any key, because the relationship travels with the numbers.

Each degree has a job

Some degrees rest, others pull

The degrees are not equal. Some feel like resting places; others feel like they are leaning somewhere. These tendencies are what give a melody its sense of movement and arrival:

The other degrees have gentler roles — 2 and 4 tend to step toward neighbours, 3 carries the bright major quality, 6 leans toward 5 — but 1, 5 and 7 are the three to feel first. You do not need to memorise the list. Just start hearing the tonic as “1,” the dominant as the strong note five steps up, and the leading note as the one straining back home. That instinct is exactly what later makes chords, cadences and whole progressions make sense rather than seeming arbitrary.

The technical names of the seven degrees

The three above are the ones to feel first. But each degree also has a proper name, and examiners use them constantly — so here is the full set for reference. Skim it now; it will sink in as you meet the names in context.

What a key signature actually is

A scale and its key signature are the same information written two different ways.

• The scale is the information spelled out in full — G A B C D E F♯ G, note by note in order.
• The key signature is that same information compressed into a symbol printed once at the start of every line, so the composer does not have to mark every individual note.

That is all a key signature is. Read “one sharp at the front” and you are reading “G major” (or E minor). Build the scale and you already know the key signature — they are the same fact expressed two ways.

What T-T-S-T-T-T-S secretly implies

You already know that T-T-S-T-T-T-S generates every major scale. The important Grade 4–5 question is not how to build the scale — you can do that — but what that pattern forces. Once the pattern exists, intervals, scale degrees, chord qualities and harmonic function all follow automatically. This section makes those implications explicit.

The first implication is interval quality. An “interval” is the gap between any two notes, named by how many letter names it spans: a second spans two adjacent letters, a third spans three, a fourth spans four, and so on to an octave (eight). Whether an interval is “major”, “minor”, or “perfect” is determined by exactly how many semitones the pattern places between those scale positions.

The “perfect” intervals — fourth, fifth, octave — are called perfect because they are the most acoustically stable. They do not come in major and minor versions; they are simply perfect (or, if altered by a semitone, augmented or diminished). The second, third, sixth and seventh each have major and minor forms, where the minor is one semitone narrower than the major.

The pattern on the keyboard

The dominant and leading note

The fifth note of a scale is the "dominant". The seventh note — a semitone below the tonic — is the "leading note". The leading note has a particularly strong upward pull toward the tonic, which is why it appears in the harmonic minor (where the seventh is raised specifically to recreate this pull in a minor context).

How many major scales are there, exactly?

This deceptively simple question has three defensible answers, and understanding why is a genuine test of whether you think in sounds or in symbols.

Twelve — by sound

An octave has twelve pitches. The major pattern can start on any of them, so there are twelve major scales by sound. By this count B♭ major and A♯ major are the same scale, because in equal temperament they are played on identical keys and sound identical.

Fifteen — by key signature

Standard notation uses fifteen major key signatures: seven sharp keys (G D A E B F♯ C♯), seven flat keys (F B♭ E♭ A♭ D♭ G♭ C♭), and C major. Three sounds appear twice under enharmonic spellings: C♯ = D♭, F♯ = G♭, and B = C♭. These fifteen are exactly the entries on the circle of fifths.

Twenty-one or more — by spelling

If you treat every distinct tonic spelling as a separate scale, the count grows. Each of the seven letters can take a flat, a natural, or a sharp — C♭ C C♯, D♭ D D♯, and so on — giving twenty-one possible tonic spellings, each of which can theoretically carry a major scale. Some of these require awkward spellings: A♯ major, spelled correctly, runs A♯ B♯ Css D♯ E♯ Fss Gss — full of double sharps, mathematically valid but unusable in practice, which is exactly why B♭ major is written instead. Admit double sharps and double flats as tonics and the theoretical count extends without limit.

Sharp or flat? Choosing the spelling

When a black key could be written either way (C♯ or D♭), the choice is not arbitrary. A handful of conventions decide it — and ABRSM expects you to know them.

Rule of thumb: key signature → then direction → then function. When they conflict, the key signature usually wins, and you avoid mixing a sharp and its enharmonic flat in the same phrase.

A key signature is just the scale, written once

Here is the equivalence worth saying plainly. When you work out a major scale, some notes come out sharp or flat — G major needs F♯, D major needs F♯ and C♯, and so on. The key signature is simply those sharps or flats collected and printed once at the start of every line, so the composer does not have to mark them on every single note.

So these are two views of the same thing:

• The scale is the pattern spelled out, note by note.
• The key signature is that same pattern compressed into a few symbols at the front.

This is why you never have to memorise key signatures as a separate table. If you can build the scale, you already know its key signature — they are the same fact, written two ways. Read “two sharps at the front” and you are reading “D major” and vice versa.

Identifying intervals from notation

In Essentials an interval was a shape — a fixed distance you could slide along the keyboard (revisit the interval band →). Here we name that distance precisely from the written stave.

To name an interval precisely, two steps:

1. Count the letter names (inclusive) to get the number: C to E is a third (C, D, E = 3 letters).
2. Count the semitones to determine the quality:
   • 2nds: 1 semitone = minor second; 2 = major second
   • 3rds: 3 = minor third; 4 = major third
   • 4ths: 5 = perfect fourth; 6 = augmented fourth
   • 5ths: 6 = diminished fifth; 7 = perfect fifth; 8 = augmented fifth
   • 6ths: 8 = minor sixth; 9 = major sixth
   • 7ths: 10 = minor seventh; 11 = major seventh
   • Octave: 12 = perfect octave

Works from any starting note regardless of key. E♭ to B is a fifth by letter count (E-F-G-A-B = 5); by semitones E♭ to B = 8 = augmented fifth. The key signature does not affect the method — just count the chromatic semitones between the two actual notes.