Guitar-friendly keys
The chart above may seem intimidating at first because of the sheer number of chords, but one of the main purposes of the capo is to move keys around, so you really only need to know how to play all seven chords in a couple of keys (instead of 12). The five guitar-friendly keys are C, A, G, E, and D.
| I | ii | iii | IV | V | vi | vii° |
| C | Dm | Em | F | G | Am | Bdim |
| G | Am | Bm | C | D | Em | F#dim |
| D | Em | F#m | G | A | Bm | C#dim |
| A | Bm | C#m | D | E | F#m | G#dim |
| E | F#m | G#m | A | B | C#m | D#dim |
To make things even simpler, the vii° chords are rarely used in pop songs, so you can think of each key as having only six chords. Notice also how many of the chords overlap among the different keys. In total, you only have 14 chords to learn: C, D, E, F, G, A, B, C#m, Dm, Em, F#m, G#m, Am, Bm.
Trying It Out
So now that we’ve gotten all of the theory out of the way, let’s begin to look at how to adjust the keys of songs that aren’t in guitar-friendly keys. We’ll use the chorus of “A Thousand Years” by Christina Perry as an example.
This song is in the key of Bb. The chord progression of the chorus is as follows:
Chorus in Bb
|Bb |Bb F |Gm |Gm F |
|Eb | Eb | F | F |
As you can tell, every single chord in the chorus is a barre chord. There’s nothing wrong with barre chords, and it’s good to know how to play them, but they tend to tire your hands out (if you use incorrect technique), and they don’t particularly sound good (in my humble opinion).
The first thing you want to do is write in the function below each chord. This will make it a lot easier to transpose the key.
Chorus in Bb
|Bb |Bb F |Gm |Gm F |
I I V vi vi V
|Eb | Eb | F | F |
IV IV V V
Now that we’ve written in the function for each chord, we’re ready to transpose the key of the chorus to a guitar-friendly key.
