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KEY SIGNATURES · BEGINNER'S GUIDE

How to read key signatures

A key signature tells you which notes are normally sharp or flat throughout a piece. Learn the pattern for major keys first, practise identifying them, then see how the same signatures also describe minor keys.

Start with major keys ↓Practise major key signatures →

What is a key signature?

The key signature is the group of sharps (♯) or flats (♭) written just after the clef. Instead of writing an accidental every time the same note appears, the key signature tells you that alteration applies throughout the music unless a later accidental temporarily changes it.

Start with one simple idea: C major has no sharps or flats. As you move around the Circle of Fifths, sharps or flats are added one at a time in a fixed order.

Major key signatures

Major keys are a good place to learn the system because the pattern is highly regular. You only need to know the order in which sharps and flats appear and two quick identification rules.

ORDER OF SHARPS
F♯ · C♯ · G♯ · D♯ · A♯ · E♯ · B♯
ORDER OF FLATS
B♭ · E♭ · A♭ · D♭ · G♭ · C♭ · F♭

How to identify a major key with sharps

1

Find the last sharp in the key signature.

2

Move up one semitone. That note is the major key. Example: F♯ is the last sharp in G major; one semitone above F♯ is G.

How to identify a major key with flats

1

When there are two or more flats, the second-to-last flat gives the major key. B♭ + E♭ therefore means B♭ major.

2

The exception is F major, which has only one flat: B♭.

Now practise the major keys

The exercise starts with C, G and F major, then gradually expands to all 15 standard major key signatures.

Open Major Key Signature Practice →

Interactive Circle of Fifths

Click a key to see its key signature and scale on the staff and the same notes on an interactive piano. Start with major keys, then reveal the related minor keys when you are ready.

Circle of FifthsMajor outside
Minor inside
C Major · C – D – E – F – G – A – B – C
Click any key in the circle to explore it.
Scale notes are highlighted softly. Altered notes are highlighted more strongly.

What about minor key signatures?

A minor key uses the same key signature as its relative major. For example, A minor and C major both have no sharps or flats; E minor and G major both have one sharp; D minor and F major both have one flat.

The relative minor is found a minor third below its major key. In the Circle of Fifths above, the minor keys sit inside their related major keys so the relationship is visible immediately.

C Major ↔ A Minorno sharps or flats
G Major ↔ E Minor1 sharp
F Major ↔ D Minor1 flat
Important: the key signature alone can correspond to a major key or its relative minor. To decide which one a piece is actually in, you also look at the music itself: its tonal centre, phrases, cadences and altered notes. The interactive examples here use the natural minor scale to show the notes belonging to each minor key signature.

Practise Major + Minor together

Now identify each key signature as a relative major–minor pair, then compare both scales on the staff and piano.

Practise Major + Minor Key Signatures →

Ready to test yourself?

Use the key-signature exercise to identify major keys from the staff with immediate visual and piano feedback.

Practise Major Key Signatures →

Continue learning

Next, see how key signatures define the notes of major and minor scales.

Next: Learn Music Scales →