Constructing Diatonic Chords from a Major Scale
Diatonic chords are chords that naturally occur within a key. They contain only the notes found in the scale (or key) that you’re working in. For new songwriters this is a must know concept for your chords to sound right.
Looking back, if there was one concept I wish my high school music teacher would have taught me it would have to be diatonic chords. It wasn’t until college that I really understood them and at that point so many unanswered questions about how songs are written and how to know which chords go together were answered for me. If you’re in the same boat as I was this should be a huge help to you. Here we go…
Finding the Chords
There are seven diatonic chords in every key, each chord built from one of the 7 notes in the scale. For example, take the G major scale:
G Major Scale
G A B C D E F#
If you’re playing a song in G major your root chord will be a G major chord. That is, the chord constructed from the root note of the G major scale. To construct a chord you simply stack thirds from the root of the scale. Check out the lesson on triads if that’s new to you. OK, so check out this list of all 7 diatonic chords in the key of G major.
Diatonic Chords in the Key of G Major
G Am Bm C D Em F#dim D E F# G A B C B C D E F# G A G A B C D E F#
See how that works? If you stack thirds from each note in a major scale into triads you’ll have every diatonic chord for that key. Each one of these chords will sound good in that key. We have a few major chords, a few minor chords, and a diminished chord to top it all off. These chord types occur naturally when we construct chords by the notes available in the scale. This pattern of chords holds true for any major scale no matter what key you’re in.
Diatonic Chord Formula for a Major Key
1(Major) - 2(minor) - 3(minor) - 4(Major) - 5(Major) - 6(minor) - 7(diminished)
Check out the list of major scales to help visualize this!
What about those roman numeral chords?
Have you ever been jamming with someone and they call out “go to the 5!”, or looked up chords online or in a songbook and they look like this “I vii IV V”? It’s common grounds to refer to a chord within a key by it’s scale degree using roman numerals. This way it doesn’t matter what key the song is in for you to know what chord to play. Using this naming convention also specifies a certain ‘sound’ since each diatonic chord has it’s own function within a key (see diatonic chord progressions for more info). For example, a IV chord in G major will have that same ‘sound’ as a IV chord will in C# major. When written, major chords are generally upper case roman numerals, and minor chords lower case. Here’s the diatonic chord formula again but using roman numerals:
Diatonic Chord Formula for a Major Key (Roman Numerals)
I - ii - iii - IV - V - vi - vii°
Since the vii° chord is diminished we add the ° symbol to indicate this.