Key Signatures

A key is a home note plus the scale built on it: in G major, G is home and the notes come from the G major scale, with one sharp, F♯. Rather than write the ♯ before every F, music writes it once at the start of each line: the key signature (see Reading Music).

The order of sharps and flats

Sharps are always added in the same order, and so are flats. The sharps come in the order F C G D A E B; the flats in the exact reverse, B E A D G C F. A key with three sharps always has the first three: F♯, C♯ and G♯.

Look closely: each sharp is a 5th above the one before, F up to C up to G … That's the circle of fifths again. Each step clockwise on the circle adds a sharp (or takes away a flat); each step anticlockwise does the opposite.

All the key signatures

Each signature belongs to one major key and one minor key, its relative minor:

C major and the sharp keys

Flat keys

Three keys can be written two ways: G♭ and F♯, D♭ and C♯, B and C♭ sound the same. Musicians usually pick the one with fewer signs: D♭ (five flats) rather than C♯ (seven sharps), B (five sharps) rather than C♭ (seven flats). G♭ and F♯ both have six, and both are used.

Tricks to name the key

• Sharps: the last sharp is a half step below the major key. Three sharps end on G♯, so it's A major.
• Flats: the second-to-last flat names the major key. Three flats are B♭ E♭ A♭, so it's E♭ major. (One flat is the exception: F major.)
• Minor: find the major key, then go three half steps down, which is always two letters down: A → G → F♯, so A major's relative minor is F♯ minor. More on that on the next page.

Try it

Pick a key's root note, then major or minor, to see its signature and its scale. Click a note to hear it.

D major: F♯ C♯. The last sharp is C♯. A half step up from it is D: D major.