Understanding Key Signatures

This lessons covers the basics of key signatures, how to read them, and how to remember them.

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Ultimate Guitar
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A key signature is a collection of every accidental (sharps and flats) in a scale/key. Key signatures are important, as they allow us to identify what key a piece of music is in. Key signatures only identify major keys. Every major key has a relative minor key, though. Which will be explained later in this lesson.

Key signatures are used so that we don't have to write sharp or flat signs next to every note.

Key signatures are written using either sharps, or flats.

The keys that use sharps in their key signatures are:

G, D, A, E, B, F#, C#

The keys that use flats in their key signatures are:

F, Bb, Eb, Ab, Db, Gb, Cb

You will notice that the key of C is not mentioned above. That is because the key of C contains no sharp or flat notes. On a keyboard, the C major scale is only the white notes, from C to C, and contains no black notes. Therefore, if there is no key signature in a piece of music, it is in the key of C major (or it's relative minor, A minor).

The table below shows the key, and the number of sharps in that key.

Sharp key signatures

C -- 0

G -- 1

D -- 2

A -- 3

E -- 4

B -- 5

F#-6

C#-7

To remember the order of the sharp key signatures this sentence can be used:

Good Dogs Always Eat Big Fat Cats

The table below shows the key, and the number of flats in that key.

Flat key signatures

C -- 0

F -- 1

Bb -- 2

Eb -- 3

Ab -- 4

Db -- 5

Gb -- 6

Cb -- 7

To remember the order of the flat key signatures this sentence can be used:

Flats Become Easier After Drinking Guinness Cold

Now that you know how many sharps/flats are in each key, you need to know which notes are sharp/flat in each key.

A great technique for remembering this is using the sentences:

Father Charles Goes Down And Ends Battle (Order of the sharps in a key signature)

&

Battle Ends And Down Goes Charles' Father (Order of the flats in a key signature)

The sharps and flats in a key signature appear in this order in key signatures, and are also written on the stave in this order.

So, for example, lets look at the key of A major. We know that A major contains 3 sharps, because "Good (1), Dogs (2), Always (3)..."

Now, we need to know what notes these 3 sharps are. So.. Father (1), Charles (2), Goes (3) ...
So we know that the three sharps in A major are F#  C# and G#

Lets look at another example, this time a flat key, Db major.

We know that Db major contains 5 flats because 'Flats (1), Become (2), Easier (3), After (4), Drinking (5)...'

We also know that these flats are Bb, Eb, Ab, Db, Gb... Because 'Battle (1), Ends (2), And (3), Down (4), Goes (5)...'

This method for memorizing key signatures is among the greatest methods, as with time, you naturally learn the amount of sharps and flats in the different keys, and the order of the sharps and flats, without saying the sentences.

Relative Minor Keys

The relative minor scale/key of every major scale/key is found by looking at the sixth note of the major scale. The table below shows this:

Sharp key signatures:

C Major -- A Minor

G Major -- E Minor

D Major -- B Minor

A Major -- F# Minor

E Major -- C# Minor

B Major -- G# Minor

F# Major -- D# Minor

C# Major -- A# Minor


Flat key signatures:

C Major -- A Minor

F Major -- D Minor

Bb Major -- G Minor

Eb Major -- C Minor

Ab Major -- F Minor

Db Major -- Bb Minor

Gb Major -- Eb Minor

Cb Major -- Ab Minor

To determine if a piece is in the major or relative minor key, you have to look at the piece in more detail. As a very basic rule, you can look at the first and last notes/chords of a piece. For example, if the key signature of a piece has 2 flats, it could be Bb major or G minor. If the last chord in this piece is a Bb major, you know the key is Bb major. If the last chord of the piece is G minor, you know the piece is in G minor.

This is a lot of information to take on board all at once, and it can take a bit of time for this to really cement itself in your head, but the more you revise it and use it, the easier it becomes to understand and the better you get at it!

Getting this basic piece of theory down will allow you to move on to more complex things too, such as using scales, harmony, modes and more!

Hopefully you find this lesson helpful! If anyone has any questions, please post a comment and I will try to answer it with a reply!

Cheers, Dom!

20 comments sorted by best / new / date

    Dom Hawthorn
    Sorry!! Spotted a mistake I've made... The 'C Major - A# Minor' should be 'C# Major - A# Minor' ... Silly typo! My bad. Hope this doesn't confuse anybody!
    rekuzu
    this is a great lesson for music theory novices, like me. thanks!
    paramore_fans
    There is no Cb neither is Fb. There is no B# neither is E#
    NeoMvsEu
    This is an ignorant comment. There are 12 distinct pitch classes in the common Western system; however, each has many possible names that depend on theoretical context. Scales are made up of fixed scale degrees, and accidentals fit the pitches to the scale. Gb major is Gb Ab Bb Cb Db Eb F Gb. Each natural note appears once per cycle, and then the natural notes are altered to fit the scale steps.
    kurdtdcobain
    Yes, there are, they're just theoretical keys. Cb is a real key; 7 flats. Fb is a theoretical key with 8 flats. B# is a theoretical key with 12 sharps and E# is a theoretical key with 11 sharps
    xonty
    It's not just theoretical for the sake of it, since no one would ever use E# major instead of F. It's more like using and E# in F# minor. Even before getting into altered harmony, you can get fairly common stuff like the Hendrix Chord (i.e. E7#9, which has an F double sharp).
    NeoMvsEu
    Maybe not as a global key, but maybe in a section in A# minor, the dominant resolution would be E# major, not F.
    whiteouteyes
    Is your picture of the staff showing the key of A major because it was an example in the lesson or is it just coincidence?
    Dom Hawthorn
    I didn't choose the picture haha! The moderator may have chosen it for that reason, but it could just be a coincidence!
    whiteouteyes
    Oh, I don't know what you are and are not in control of when you submit something here lol I'll be looking at all the pics in a different light now
    DeviousByNature
    "A key signature is a collection of every accidental (sharps and flats) in a scale/key" This isn't exactly true, technically an accidental is when a sharp, flat or a natural note in the stave is out of key according to the notes in the key signature, rather than sharp/flat being accidentals themselves whatever the context.
    Dom Hawthorn
    True.. but here I'm using the term 'accidental' to refer to the sharp/flat signs themselves.. It's extremely common for key signatures to be described in this way, and is how they are described in many many music theory books. Thanks for mentioning that though, as it will probably help some readers avoid confusion