What is a diatonic chord?
It's basically a fancy term for a chord that's within your key.
Knowing what the diatonic chords in your key are will save you SO much time when you're songwriting and help you avoid the trial-and-error method of writing chord progressions. (I think we've all been there...)
To find out if a chord is diatonic to the key, think of the key signature (which notes are sharp or flat. If the three notes in your chord match your key signature, that means the chord is diatonic!
(Print out the key signatures reference sheet if you're having trouble remembering them!)
Though you always CAN use non-diatonic chords (which can a really cool effect!), if you're just starting out, I'd recommend getting comfortable with using the diatonic chords before you start branching out. Most songs use only diatonic chords, anyways!
The pattern of diatonic chords in any major key
Since every key has 7 unique notes in the scale, each key will also have 7 unique diatonic chords. There's actually a really simple pattern to remembering what the diatonic chords in any major key are.
We're going to borrow a Roman Numeral system from classical music to remember this pattern:
I ii iii IV V vi vii°
The number of each Roman Numeral refers to the note the scale that each chord is based on. (Ex. in C major, the I refers to a C chord, the ii refers to a D chord...etc.)
Upper/lower case refers to major and minor (the I chord is major, ii is minor...)
The little circle after the vii° chord refers to a diminished chord - which is another type of chord similar to minor.
So underneath the roman numerals, write out the literal chords in whatever key you're playing in.
So next time you're writing a song, write out these Roman Numerals and write the chords in your key that they refer to underneath them.
Here's what this would look like in C major:
I ii iii IV V vi vii°
C Dm Em F G Am Bdim
And now you have 7 chords to choose from when you're writing your song!
P.S. Try using this chord finder worksheet to guide you through the process! Or if you need a more in-depth explanation, check out the Music Theory for Songwriters Course.
