A key signature is written directly after the clef and makes notes sharp or flat the entire way through the piece.
The sharps or flats in a key signature are written in a very specific order, as shown in the rhymes as well as the example below. When writing a key signature, you should ALWAYS put them in this order.
There is a useful rhyme for remembering the order of sharps in a key signature.
Father Charles Goes Down And Ends Battle
The rhyme for flats is the same as for sharps, but in reverse order.
Battle Ends And Down Goes Charles’s Father
How to work out the key signatures
C major and F major are both exceptions to the rule shown below so you will just need to remember them.
C major has no sharps or flats.
F major has one flat- B♭.
Rule- sharp keys in major
There are a few easy steps that will lead you to the key signature of a key, as shown below.
- Find the tone before the key that you want, for example for the key of D major the tone before is C.
- Using the appropriate rhyme above, take all of the ♯’s up to and including the tone that you worked out in step 1. Using the example of D major, taking all of the tones including C gives us F♯ and C♯ for Father and Charles.
Rule- flat keys in major
Other than F major, which is discussed under the anomaly section, all flat keys have the word ‘flat’ in the name, such as B flat major or D flat major.
Just like the sharp keys, flat keys have an easy system to work out the key signature. It is different to the one for sharp keys, so make sure you don’t mix them up!
- The penultimate flat in the key signature is the name of the key
- Find the letter name of the key in the appropriate rhyme above and take all of the flats before it, then add the next one in the rhyme as well.
For example, for the key of D♭ major we find D in the rhyme, which is the fourth point of the rhyme, then we add the next as well. This gives us five flats; Battle Ends And Down Goes.
F♯ and G♭ are the same key, the only difference is that one uses sharps and the other flats. Because they are enharmonic equivalents they use the same series of pitches.