Each Major key is associated with a relative minor key. Major keys and their relative minor keys have exactly the same key signatures.
The relative minor key starts a minor third (third containing 3 half steps
How to find the relative minor key from a major key?
There are two methods to find the relative minor key from a Major key, I will explain those two methods:
Method #1:
Tonic (first degree of the scale) of the relative minor key is a minor third below the tonic of his relative Major key. Don't forget that a minor third is contains 3 semitones.
Method #2:
Tonic (first degree of the scale) of the relative minor key is the degree VI of his relative Major key.
Examples, how to find the relative minor key from a major key?
Finding the relative minor key of C major key
Here we will try to find the relative minor key of C major key:
Method #1:
Tonic of the relative minor key is a minor third below the tonic of C major key.
* Tonic of C major is : C
* a minor third subtracted from C is: A
-> so the relative minor key of C major key is A minor key
Method #2:
Tonic of the relative minor key is the degree VI of his relative C major key, you must count:
I: C
II: D
II: E
IV: F
V: G
VI: A
-> so the relative minor key of C major key is A minor key
And don't forget that there are several kinds of minor keys:
A natural minor scale
A harmonic minor scale
A ascending melodic minor scale
A descending melodic minor scale
Finding the relative minor key of A flat major key
Here we will try to find the relative minor key of A flat major key:
Method #1:
Tonic of the relative minor key is a minor third below the tonic of A flat major key.
* Tonic of A flat major is : A flat
* a minor third subtracted from A flat is: F
-> so the relative minor key of A flat major key is F minor key
Method #2:
Tonic of the relative minor key is the degree VI of his relative A flat major key, you must count:
I: A♭
II: B♭
II: C
IV: D♭
V: E♭
VI: F
-> so the relative minor key of A flat major key is F minor key
And don't forget that there are several kinds of minor keys:
F natural minor scale
F harmonic minor scale
F ascending melodic minor scale
F descending melodic minor scale