Determining The Chords For Any Key

November 19th, 2005 Print Tip E-mail Tip

It's fun and easy (or maybe distasteful and difficult) to figure out the diatonic chords for any key. Diatonic means the chords are created only from notes found in a given scale. This article will deal strictly with diatonic chords comprised of three different scale notes, which are called triads. We're also just looking at chords that are contained in, and derived from, major key scales (though as you'll see later a given set of chords is also used intact in a key's "modes").

First take a look at the lesson "The 12 Major Scale Spellings" in the "Scales" folder. Observe how each note in each of the keys has a "scale degree" Arabic numeral above it. This numerals will give us the universal formulas to determine a given scale's diatonic chords.

In C they are:

For example here are the 7 diatonic triads in the key of C Major (we'll examine diatonic 4-note chords later):

As you can see, all you have to do is start with one note, skip the next, use the next, skip the one after, and then take the next. The Roman numeral chord designation give you a universal representation of the chords for any key. So, if someone says, "Let's play a I - VIm- IV - V in C Major", you'll know the chords to use---C - Am - F - G. If you then want to use that exact chord progression in Eb, you just extract the I - VIm - IV - V chords in Eb which are the Eb - Cm - Ab - Bb triads. If you chart out a repetitive scale "to infinity", it's easier to see the "take one, skip one" approach. This will be covered also when we look at diatonic 4-note chords.

C Scale to infinity: