Relative keys have the same key signature (number of sharps or flats). For every note in the chromatic scale there is a relative major key and a relative minor key.
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The two keys are clearly different because they start on a different tonic note and one scale is major (sounds “happy”) whilst the other is minor (sounds “sad”).
However, they sound related because they share the same number of sharps and flats and so you can easily play one after the other without it sounding horribly discordant!
Understanding this relationship between the relative majors and minors is really useful when you are composing as it makes it very easy to modulate (change key) from the relative major to the relative minor or vice versa. This will make your compositions instantly more interesting.
How to work out the Relative minor
The good news is that it’s really easy to work out the relative minor of a major key!
If you want to get from the relative major to the relative minor you simply need to count down 3 semitones from the relative major. Have a look at this example on a keyboard:
You can see that if I want to get from C major to its relative minor I start on C and count down 3 semitones and reach A.
Therefore, the relative minor of C major is A minor.
Here’s another example of the relative minor of E major:
If I want to get from E major to its relative minor, again I count down 3 semitones and reach C sharp.
So, the relative minor of E major is C sharp minor.
How to work out the Relative major
Again, it’s very easy!
All you need to do is to count up 3 semitones from the relative minor and you will reach the relative major. Have a look at this example:
If I want to get from F sharp minor to its relative major.
Count up 3 semitones and I get to A major.
So, the relative major of F sharp minor is A major.
Relative Keys Chart
You can see that it is easy to work out what the relative major/minor of a key is.
However, you do need to know how many sharps/flats are in the related keys in order to be able to use them in your composition.
I have put together a chart showing all the relative major and minor keys together with their respective key signatures.
This should help you as you get started:
Composing Using Relative Keys
Changing key from the relative major to the relative minor is a great way of introducing contrast in a piece of music.
It can also provide a clear sense of structure to a piece.
Have a look/listen to this example.
It is a piano piece called Prelude 18 – The Lily.
You can see/hear how the piece starts in A major.
It then modulates to the relative minor – F sharp minor.
I don’t have to use any pivot chord or modulating section of music as the two keys have the same key signature.
This creates a contrasting section with a more melancholic feel before modulating back to the relative major for the concluding section.
I hope this example inspires you to use relative major/minor modulations in your own composing.