How to Read Key Signatures
A key signature is the group of sharps or flats written after the clef. It tells you which notes are normally sharpened or flattened throughout the music.
Practise key signaturesWhat you’ll learn
- C major has no sharps or flats
- G major has one sharp: F sharp
- F major has one flat: B flat
- D major has F sharp and C sharp; A major adds G sharp
A piece has one sharp, F sharp, in its key signature. What major key is it in?
G major.
G major uses F sharp to preserve the major-scale pattern. Every written F is played as F sharp unless a natural sign changes it.
Why this matters
Key signatures appear early in graded theory and remain essential for scales, intervals, chords and analysis. Start with C, G and F major, then add keys gradually.
Common mistakes to avoid
- Treating a key signature as if it applies only to the line where it is printed
- Mixing up G major (one sharp) and F major (one flat)
- Adding a sharp or flat symbol beside every affected note when the key signature already covers it
Ready to practise?
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