The circle of fifths is a great shortcut and a fundamental tool for all songwriters. Once you understand how to use it, it can make writing songs so much easier!
The circle of fifths helps us understand the key signature of a song a how to use it. This helps us with the harmony and the melody of our song and can be a great advantage when writing songs and creating chord progressions.
What is a Key?
The key of your song is the group of notes around which your song is based, which corresponds to a specific scale.
Consider the key of your piece of music like a box which holds notes; the box will hold by default only the notes which correspond to that specific key, creating a foundation for your harmonies and melody.
If you know the key of the song, you also know the scale, how many sharps or flats are used, the home note and much much more.
You can also think “outside the box” of your key and add notes which aren’t specific to that key; most of the time though, the notes will come from a key which is quite close to the original. This means that it may differ from the first key by one or two sharps or flats.
Keys and Scales
Keys and scales are related; a song in F major will be based on the F major scale, just like a song in C major will be based on the C major scale. This does not mean that all the chords in the scale are major or minor though.
In order to construct a major scale, you need to follow the following rule:
TONE – TONE – SEMITONE – TONE – TONE – TONE – SEMITONE
That’s it. You can start your major scale from any note, but this is the relationships the notes need to have with each other.
For example, if I wanted to construct an F major scale my notes would be:
F – G – A – B♭ – C – D – E – F
( T – T – St – T – T – T – St)
Each major key is “related” to a minor key. The relative minor key will have exactly the same sharps or flats as the related major key. However, it’s home note is placed exactly 3 semitones (minor third) below the home note of the major key.
Therefore, for example, the relative key of F major is D minor. D is in fact placed exactly 3 semitones below F. This means that they share exactly the same sharps or flats which, as we discovered before, is only one and is B♭. This also means that the major key and its relative minor share the same key signature.
The Circle of Fifths
The circle of fifths is an easy way to understand which sharps or flats are in a major key, and therefore also in the relative minor key.
Outside the circle, you see the major keys. Inside the circle you can find their relative minor keys. The first key at the top is C major, which has no sharps or flats. In piano terms, it’s made up only of white keys. Its relative minor is A minor.
Going clockwise, each key is one fifth over the previous one and has one more sharp than the previous one. Counterclockwise, each key is one fifth under the previous one and has one more flat that the previous one.
Clockwise: C – G – D – A – E – B – F# – C#
Counterclockwise: C – F – B♭ – E♭ – A♭ – D♭ – G♭ – C♭
There are many tricks to learning which sharps and flats are in a specific key. My favourite one is to memorise the sequence of sharps, because they will always appear in the same order.
The sequence of the 7 sharps used follows the circle of fifths but starts from the F before the C at the top. The sequence is therefore:
F – C – G – D – A – E – B
The sequence for the flats is the same, but backwards:
B – E – A – D – G – C – F
C major has no sharps or flats. Going clockwise, G major will have one sharp…the first one from the sequence, which is F! D major will have two (F# and C#), A major will have three (F#, C# and G#) and so on. Going counterclockwise, F major will have one flat (B♭, as it’s the first one from the sequence), Bb major will have two flats (B♭ and E♭)…you get the point!
The relative minor key will have the same key signature but start from a different note; if we use exactly the same notes as the major key to form the minor scale, this will be a natural minor scale. There are other types of minor scales but it’s important to be familiar with the natural minor scale first.
If a key uses sharps it won’t use flats and vice-versa. This is true for all keys but doesn’t actually apply to all scales; it does apply, however, to all major and all natural minor scales. An exception, for example, are some minor harmonic scales, such as G minor harmonic.
Here’s a summary you can use for all scales!
A Trick for Keys Which Use Sharps
There’s a pretty easy trick for those scales that use sharps. All you have to do is start from the tonic (the home note) of the key and go down a semitone. The note you get is the last sharp in the sequence we know, so the sharps will be that last one plus all the others in the sequence.
Sequence: F C G D A E B
A major: down a semitone is G#. G# is our last sharp, so by reading the sequence up to G# we have F#, C# and G# as sharps in the key of A major.
A Trick for Keys Which Use Flats
There’s a trick for flats too, which works for every key except F major, which you might as well memorise.
In the reverse sequence, we take all the notes up to the tonic of our scale plus one.
Sequence: B E A D G C F
Ab major: Read the sequence up to A♭ and then add one more. A♭ major will therefore have B♭, E♭, A♭ and D♭.
Knowing how to use the circle of fifths makes it so much easier to structure your song and create effective chord progressions and melodies. Practice by writing the key signature and notes in specific keys and eventually, this will become an easy method to understand which notes are in a key.