Accidentals: Sharps, Flats, and Naturals

Core Idea

Accidentals modify the pitch of a note: sharps raise a pitch by one semitone, flats lower it by one semitone, and naturals cancel previous accidentals. They are essential for notating chromatic pitches and creating pitches outside the diatonic scale.

How It's Best Learned

Write accidentals on a staff, play them on an instrument, and listen to the sound changes. Practice identifying accidentals in written music.

Common Misconceptions

Sharps and flats are not specific pitches—they're modifications of existing notes. A sharp doesn't always mean 'higher' in absolute terms; F# is lower than G.

Explainer

You already know the seven natural note names — A, B, C, D, E, F, G — and how they repeat across octaves. But these seven notes only account for seven of the twelve pitches within an octave. The remaining five pitches are the chromatic pitches, and accidentals are the notation symbols that give us access to them.

A sharp (♯) raises a note by exactly one semitone — the smallest step available in standard Western music, equivalent to moving one key to the right on a piano. So C♯ is one semitone above C, and F♯ is one semitone above F. A flat (♭) lowers a note by one semitone: B♭ is one semitone below B, E♭ is one semitone below E. The natural sign (♮) cancels a previous accidental, returning a note to its unmodified pitch. If a piece is in a key that includes B♭ (meaning every B in the piece is flattened by default), writing B♮ explicitly tells the performer to play the natural B instead.

The key insight the Common Misconceptions section points toward is that accidentals are relative modifiers, not absolute labels. "F♯" doesn't name a unique, fixed thing the way "F" does — it names the result of applying a sharp to F. That's why, on a piano, you can reach the same physical key either as C♯ (C raised) or D♭ (D lowered): two different names, one sound. This is called enharmonic equivalence, which you'll study soon. For now, the important thing is to understand that a sharp or flat always belongs to a named note and tells you which direction and by how much to adjust it.

In written music, accidentals apply for the rest of the measure in which they appear, then reset. If you see a C♯ in measure 3, every subsequent C in that same measure is also C♯ unless marked otherwise with a natural sign. This rule — accidentals last for the measure — is one of the most common sources of reading errors, so it's worth memorizing explicitly. Accidentals are how composers reach pitches outside the seven-note diatonic scale of a given key, whether to create passing color, signal a key change, or introduce the chromatic richness of chords like secondary dominants (which you'll study later). Mastering accidentals at the reading level is the foundation for all of that later work.