Accidentals: sharps, flats and naturals while sight-reading
How long a sharp or flat lasts, what naturals and courtesy accidentals mean, and how to stop missing them.
Key points
- An accidental lasts until the barline, on that line or space.
- Ties carry it across the barline.
- Courtesy accidentals are reminders, not changes.
An accidental is a sharp, flat or natural written in front of a note, outside the key signature. The rules are short; the hard part is noticing them while you read.
The symbols
| Sign | Name | Effect |
|---|---|---|
| ♯ | Sharp | Raise by a semitone |
| ♭ | Flat | Lower by a semitone |
| ♮ | Natural | Cancel a sharp or flat (from the key or an earlier accidental) |
| 𝄪 | Double sharp | Raise by two semitones |
| 𝄫 | Double flat | Lower by two semitones |
How long an accidental lasts
- It applies to that note and any repeats of the same line or space for the rest of the bar.
- The barline cancels it. The next bar goes back to the key signature.
- Exception: a note tied across the barline keeps the accidental for the tied note.
- In standard practice it applies only at that octave. A sharp on the F in the top line does not affect an F in the bottom space; many editors add a reminder anyway.
Courtesy accidentals
Sometimes you will see an accidental in brackets, or a natural in the bar after an accidental. These are reminders, not new instructions. Play them; they are telling you what is already true.
How not to miss them
- In your 30-second scan, sweep the page for accidentals and note the bars they occur in.
- If one note keeps being altered (a raised 7th like G♯ in A minor), the piece is probably in the minor key.
- Touch the altered black key before you start, the same way you do for the key signature.
