Lessons › Theory

Key signatures made simple

A key signature is the group of sharps or flats right after the clef. It tells you which notes are raised or lowered for the whole piece, so the composer doesn’t have to write them every time.

How a key signature works

If the key signature has an F♯, every F in the piece is played as F♯, in every octave, unless the music says otherwise. The same goes for each sharp or flat in the signature. A piece in G major has one sharp (F♯); a piece in F major has one flat (B♭).

The D major scale. The key signature turns every F and C into F♯ and C♯.

The order of sharps

Sharps always appear in the same order: F C G D A E B. One way to remember it is Father Charles Goes Down And Ends Battle. A key with three sharps has the first three: F♯, C♯ and G♯.

C♯ major: all seven sharps in order.

The order of flats

Flats run in the reverse order: B E A D G C F. The first four spell BEAD, which makes them easy to remember. A key with two flats has B♭ and E♭.

C♭ major: all seven flats in order.

Naming the key

No sharps or flats: C major (or A minor).
Sharps: go up one half step from the last sharp. The last sharp in two sharps is C♯, so the key is D major.
Flats: the second-to-last flat names the key. Three flats end in B♭, E♭, A♭, so the key is E♭ major. The one exception to learn by heart: one flat is F major.

Every major key shares its key signature with a relative minor key, three half steps lower. G major and E minor both have one sharp. To tell them apart, look at the first and last notes and any raised seventh notes (D♯ in E minor).

Sharps	Major	Minor	Flats	Major	Minor
1	G	E	1	F	D
2	D	B	2	B♭	G
3	A	F♯	3	E♭	C
4	E	C♯	4	A♭	F
5	B	G♯	5	D♭	B♭
6	F♯	D♯	6	G♭	E♭
7	C♯	A♯	7	C♭	A♭

Accidentals

A sharp, flat or natural written directly before a note is an accidental. It overrides the key signature, and it lasts until the end of the measure for that note at that pitch. The bar line cancels it.

The second F is sharp, so the third F is sharp too. After the bar line, F is natural again.

A natural sign (♮) cancels a sharp or flat, either from the key signature or from an earlier accidental in the same measure. Composers sometimes add a reminder accidental in brackets after a bar line; it is a courtesy, not a rule.

Reading in a key

Before you play, look at the key signature and say the altered notes to yourself: “F sharp and C sharp.” Many mistakes in sight-reading come from forgetting the key signature halfway through a line. It also helps to know the scale of the key, because most notes in the piece will come from it.

Choose any key in the Sight-read tab. Every note name and the playback follow the key signature, so you can hear if you forgot a sharp.

Practice in a key