How to Use Music Theory to Build Minor Triads
According to music theory, a minor triad is made up of a root, a minor third above the root, and a perfect fifth above the root. As with major triads, you can build minor triads two different ways.
Half‐step counting method
As with major triads, you can count out the half steps between notes to build a minor chord using this formula:
Root position + 3 half steps + 4 half steps (7 half steps above root)
Here, you see C minor on the piano keyboard.
Here, you see C minor on the staff. Notice the pattern of half steps between the root, the third, and the fifth.
First, minor third, and fifth method
The second way to construct minor triads is to just take the first, the minor or flat third (which means you lower the third degree of the major third one half step), and fifth intervals from a major scale.
For example, for an F minor chord, you write down the key signature for F major and then build the triad.
If you were to build an A flat minor chord, you would write the A flat key signature and add the notes, flatting the third.