How To Find Chords In Scales

A very common question from students is how we can tell which chords as "in key with" a particular scale. This came up today on /r/guitarlessons so I thought it might be worth a quick post.

I advocate learning scales in 4-fret positions following the popular CAGED method, but that's not the only way to do it. However you did it, though, hopefully you can find all the notes in the scale within "easy reach" of a particular fret. For concreteness, let's say you're playing the C major scale with your index finger at the fifth fret. Then the notes of the scale will lay out something like this:

The idea is that a chord shape is "in key" or "in the scale" (technically, "can be harmonized from the scale") if it only contains notes that the scale contains. So any chord that only uses the notes marked by blue spots is "in the key of C major". I'm putting scare quotes around all this because that isn't really what "in the key of C major" means: all I mean here is that the chord "fits with" the scale because it only contains notes that are in it.

As an example, here's the D minor bar chord at the 5th fret. Notice how all the green spots (the chord) were blue spots in the previous diagram -- that tells you that the D minor chord is part of the harmonized C major scale:

Here (big-ish file) are all the usual triads in the C major scale highlighted in the same way. Notice that the pattern of notes never changes. We just light up different notes to get chord shapes that are already buried within the scale. Some of these shapes may not be familiar to you yet, but some hopefully will be (check out D minor, E minor and A minor especially). Notice that we play all seven chords without ever leaving that four-fret position.

Based on this you can, I hope, see how to embellish a chord with nice extensions by adding extra notes from the scale. For example, here I've added the purple notes to the F chord to create an Fmaj7#11:

You can do this on the fly; no need to learn these as separate chords, just use your ears as you learn which notes do what in each position. This will greatly develop your improvisation, since it helps you to learn each note's relationship to the underlying harmony.

You can also create other harmonies out of the scale's notes such as quartal chords in exactly the same way... but that's a lesson for another day.