What does the key signature tell me?

It lists every note that is sharp or flat throughout a piece, in a fixed canonical order. Reading it tells you the key without scanning the whole melody.

Why does each key always have the same number of sharps or flats?

Because the major scale formula (W-W-H-W-W-W-H) forces a specific set of accidentals from each tonic. Going up by a fifth adds one sharp; going up by a fourth adds one flat. That is the circle of fifths.

What is a relative key?

A major key and the minor key that share the same signature are relative - for example C major and A minor. Their tonics sit a minor third apart.

How do I find a minor key's signature?

Look up its relative major: count three semitones up from the minor tonic. The signature of that major key is also the signature of the minor key.

Key Signatures

Explore every major and minor key with its sharps, flats, diatonic chords, relative and parallel keys. Then practice with two trainer modes - count the accidentals or identify the key from its signature.

Major keys

Grouped so keys with the same accidental sit together.

No accidentals

Sharp keysone to 7 sharps

Flat keysone to 4 flats

Minor keys

No accidentals

Sharp keysone to 4 sharps

Flat keysone to 7 flats

C Major

Major key

CDEFGAB

Accidentals

no sharps or flats

Relative key

Parallel key

Diatonic chords

IC
iiDm
iiiEm
IVF
VG
viAm
vii°B°

What is a key signature?

A key signature is a group of sharps or flats placed at the start of every staff line. It tells you which notes are altered throughout the piece, so the music doesn't need an accidental in front of every affected note.

Major and minor keys come in pairs that share the same signature - they are called relative keys. C major and A minor both have no sharps or flats; G major and E minor both have one sharp; and so on around the circle of fifths.

Order of accidentals

Accidentals are always added in a fixed order. Read each staircase top to bottom - every step adds one more, and its mnemonic word appears beneath the new note. A key with N accidentals uses the first N steps.

SharpsFather Charles Goes Down And Ends Battle

1♯F♯Father

2♯F♯C♯Charles

3♯F♯C♯G♯Goes

4♯F♯C♯G♯D♯Down

5♯F♯C♯G♯D♯A♯And

6♯F♯C♯G♯D♯A♯E♯Ends

7♯F♯C♯G♯D♯A♯E♯B♯Battle

FlatsBattle Ends And Down Goes Charles' Father

1♭B♭Battle

2♭B♭E♭Ends

3♭B♭E♭A♭And

4♭B♭E♭A♭D♭Down

5♭B♭E♭A♭D♭G♭Goes

6♭B♭E♭A♭D♭G♭C♭Charles'

7♭B♭E♭A♭D♭G♭C♭F♭Father

The flats are the sharps in exact reverse - so the two mnemonics are mirror images of each other.

Once you know a key's signature, its diatonic chords fall out of it. The chord library has every voicing, on piano and guitar, ready to sound out.

Open the Chord Library

Frequently asked questions

What does the key signature tell me?: It lists every note that is sharp or flat throughout a piece, in a fixed canonical order. Reading it tells you the key without scanning the whole melody.
Why does each key always have the same number of sharps or flats?: Because the major scale formula (W-W-H-W-W-W-H) forces a specific set of accidentals from each tonic. Going up by a fifth adds one sharp; going up by a fourth adds one flat. That is the circle of fifths.
What is a relative key?: A major key and the minor key that share the same signature are relative - for example C major and A minor. Their tonics sit a minor third apart.
How do I find a minor key's signature?: Look up its relative major: count three semitones up from the minor tonic. The signature of that major key is also the signature of the minor key.

What is a key signature?

Order of accidentals

Explore the chords in every key

Frequently asked questions