What Is an Accidental?

An accidental is a sharp (♯), flat (♭), or natural (♮) sign attached to a note. A sharp raises the note by one half step, a flat lowers it by one half step, and a natural cancels a previous sharp or flat. On guitar the translation is direct: sharp = one fret up, flat = one fret down.

Sharps and flats on the fretboard

Between most natural notes sits one in-between note that can be spelled two ways: the note one fret above F is F♯, and it's also one fret below G, so it's equally G♭. Same fret, same pitch, two names — that's an enharmonic equivalent. Which spelling you use depends on the key: the D major scale calls it F♯, the D♭ major scale would call its notes flats.

"Accidental" vs. key signature

Strictly, sharps and flats that are built into the key live in the key signature, and an accidental is a sharp or flat that appears mid-piece, outside the key. In everyday guitar conversation, though, "accidental" just means any sharped or flatted note — and that looser usage is fine.

Related terms

• Natural note — the seven plain letter names
• Enharmonic equivalent — F♯ and G♭ are the same fret
• Chromatic scale — all twelve notes in a row
• Key signatures explained — why keys come with built-in sharps or flats