Notes and intervals
Sharp and flat
A sharp (#) raises a note by one semitone and a flat (♭) lowers it by one semitone: on the guitar, that means one fret higher or one fret lower.
What do sharp and flat mean?
They are accidentals. A sharp (#) raises a note by one semitone; a flat (♭) lowers it by one semitone. A natural sign (♮) cancels them. There are also double sharps (𝄪) and double flats (♭♭), which shift a note by two semitones.
On the guitar it is mechanical: F is at the 1st fret of the 6th string, F# at the 2nd. B is at the 2nd fret of the 5th string, B♭ at the 1st.
Why does one fret have two names?
Between two natural notes a whole step apart, there is an in-between fret that can be named two ways. The 2nd fret of the 6th string is F# (F raised) or G♭ (G lowered). These are enharmonic equivalents: same sound, different name.
The chromatic scale is usually written with sharps going up (C, C#, D, D#, E) and flats coming down (E, E♭, D, D♭, C). Between E and F, and between B and C, there is no in-between fret.
Sharp or flat: how do you choose?
The key decides. Golden rule: in a scale, each letter appears exactly once. F major is F, G, A, B♭, C, D, E: you write B♭, not A#, otherwise you would have two A's and no B.
The key signature groups those accidentals at the start of the staff. Sharps always appear in the order F, C, G, D, A, E, B; flats in reverse: B, E, A, D, G, C, F. G major has one sharp (F#), D major two (F#, C#), F major one flat (B♭). The interactive circle of fifths shows every key signature in one click.
Exercise: the D major scale on one string
Play D major on the 4th string: open (D), then frets 2 (E), 4 (F#), 5 (G), 7 (A), 9 (B), 11 (C#) and 12 (D). Say each note name out loud. The two sharps in the key signature, F# and C#, fall exactly where the scale needs a whole step before the half step.
Then apply the same logic to barre chords. F#m: the Em shape barred at the 2nd fret (root F# on the 6th string). B♭: the A shape barred at the 1st fret (root B♭ on the 5th string). A chord's name depends only on the fret of its root.
Key takeaways
- Sharp = one fret up; flat = one fret down.
- One fret can carry two names: F# and G♭, C# and D♭.
- The key decides the spelling: each letter once per scale.
- Order of sharps: F, C, G, D, A, E, B; flats: B, E, A, D, G, C, F.
Frequently asked questions
Are F# and G♭ the same note?
On a guitar, yes: same fret, same sound. The name depends on the key: F# in D major, G♭ in D♭ major. This is called enharmonic spelling.
Do E# and C♭ really exist?
Yes, though they are rare. E# sounds like F and appears in F# major (F#, G#, A#, B, C#, D#, E#). C♭ sounds like B and appears in G♭ major. They follow the one-letter-per-degree rule.
Why is guitar music usually in sharp keys?
Because the most comfortable keys on guitar, the ones that use open strings, are E, A, D and G: all sharp keys. Horn players, on the other hand, favour flat keys like B♭ and E♭.
Related terms
Practise in the workshop
Take it from theory to the fretboard
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