Lesson 25 · Part 6, Why it is spelled that way

Sharps and flats

F♯ major and G♭ major are the same seven sounds with two different spellings, and each spelling follows from a rule.

On the staff

F♯G♯A♯BC♯D♯E♯F♯

On a treble staff, the F♯ major scale is written F♯ G♯ A♯ B C♯ D♯ E♯.

This is one octave of the F♯ major scale, written on the treble clef. Guitar and bass music is written an octave higher than it sounds, and the small 8 under the clef is the sign for that.

Why the F♯ major scale has these sharps

  1. F♯1
  2. T
  3. G♯2
  4. T
  5. A♯3
  6. S
  7. B4
  8. T
  9. C♯5
  10. T
  11. D♯6
  12. T
  13. E♯7
  14. S
  15. F♯8

A scale is a pattern of steps, and this one is T T S T T T S: a tone, a tone, a semitone, and so on. S stands for a semitone, the distance of one fret or one key. T stands for a tone, which is two semitones. The pattern is what gives F♯ major its sound, and it stays the same whichever note you start on.

The second rule is that a seven-note scale uses each letter name once, from A to G, so its seven notes take seven different letters. That is why F♯ major is spelled the way it is, rather than with whichever accidental looks tidier.

Together, the two rules leave no room for choice. If you walk the pattern up from F♯, five letters cannot keep up:

  • G♯ — the second. The pattern needs a tone from F♯, but F♯ to G is only a semitone, so G has to rise to G♯.
  • A♯ — the third. The pattern needs a tone from G♯, but G♯ to A is only a semitone, so A has to rise to A♯.
  • C♯ — the fifth. The pattern needs a tone from B, but B to C is only a semitone, so C has to rise to C♯.
  • D♯ — the sixth. The pattern needs a tone from C♯, but C♯ to D is only a semitone, so D has to rise to D♯.
  • E♯ — the seventh. The pattern needs a tone from D♯, but D♯ to E is only a semitone, so E has to rise to E♯.

None of those accidentals was a choice. Once you pick the note to start on, the pattern decides the rest, and a key signature is a record of the result.

The F♯ major scale is written with F♯, G♯, A♯, C♯, D♯ and E♯. F♯ has its accidental because that is the key, and the other notes need theirs because the T T S T T T S pattern of steps cannot be spelled from F♯ with plain letters.

The pattern of steps is the part of a scale that never changes. The letter names take sharps or flats to fit that pattern, and a key signature is a record of those sharps or flats.

F♯ major and G♭ major are the same seven sounds, and both spellings are correct. A scale uses each letter name once. If you run the major scale pattern from F♯, every letter that falls short of the pattern takes a sharp. If you run the same pattern from G♭, the letters take flats instead. Each spelling needs six accidentals, and because neither is simpler, this key is written both ways.

For the other keys with two possible spellings, one is clearly simpler. B major needs five sharps where C♭ major would need seven flats, so C♭ major is rarely used. D♭ major needs five flats where C♯ major would need seven sharps, so C♯ major is rarely used. The spelling normally chosen for a key is the one with fewer accidentals.

None of this is a matter of taste. A key signature follows from starting the pattern on a particular letter, and every accidental in it is required by the pattern. The only real choice is which letter to start from.