Enharmonic
Enharmonic describes two notes, intervals or keys that sound identical on a piano or guitar but are written with different names, such as C♯ and D♭.
What are some enharmonic notes?
On a keyboard each black key has two names: C♯ and D♭ are one key, F♯ and G♭ are another. White keys can have two names as well: E is also F♭, F is also E♯, and B is also C♭.
The idea extends beyond single notes:
- Intervals: C up to E and C up to F♭ are both four semitones. The first is a major third, the second a diminished fourth.
- Keys: F♯ major (six sharps) and G♭ major (six flats) sound the same and are written differently.
How do you know which name to use?
The key decides, because a major or minor scale uses each of the seven letters exactly once. D major is D E F♯ G A B C♯. Writing G♭ instead of F♯ would give the scale two Gs and no F, so in D major the note is always F♯.
The same rule explains the leading tone of A minor. It is G♯, a semitone below A, and not A♭, because it is the seventh letter of a scale that starts on A.
A useful habit: when a note goes up, it is usually spelled with a sharp; when it goes down, with a flat. Spelling shows where a note is heading.
What is the most common confusion?
Thinking the spelling is a matter of taste. It is not, even though the sound is identical. A wrong spelling makes a scale or chord harder to read and can rename its intervals: C–E–G is a major chord, while C–F♭–G, the same three keys, is no chord a reader would recognise.
Try it: the enharmonic intervals lesson shows how letters decide an interval’s number, and Notes and semitones maps the twelve notes on the keyboard.