A capo, which is short for capotasto, is a device that attaches to your guitar fretboard to raise the pitch of the open strings. A capo allows you to play in different positions and keys, but keep the same familiar chord fingerings you use at the end of the neck in the open position.
Another reason guitarists use capos is to take advantage of favorable chord voicings that occur only as open forms.
Transposing up to new keys with a capo is as easy as it gets. If you know how a song is played in the open position, add a capo at some other fret and duplicate the same fingerings ahead of it, as if the capo were the nut. Voilà! New key.
Taking advantage of favorable chord voicings is easy, too. If you want a song in the key of A to use the chord voicings found in the key of G, then add a capo to the second fret. Now you play the key of A’s three main chords — A, D, and E — using the fingerings and voicings of G, C, and D. If you want to stay in the key of A, but you prefer the chord voicings found in the key of E, place the capo at the fifth fret, and using fingerings for E, A, and B.
Getting back to transposing, if you want to move to a lower key, you have to work out the changes with different chord forms, as if you were playing in a different open-position key. For example, if you want to transpose down from the key of G, but still play in a key that utilizes open strings, the next key to play in is E, which is a change of three frets or one-and-a-half steps. If the key of E transposes the music too far down, add a capo to bring it up. At the first fret, an E chord becomes F. At the second fret, it becomes F#. If transposing down to E is not far enough, move backward from it to D. The key of D works well in the open position, and if it’s too low, you can always bring it up with a capo.
The keys that work best in the open position are C, A, G, E, and D. These are the same chord forms that make up the so-called CAGED system. Their relative minor keys are included. Other keys can be partially played in the open position, like F and B, but require more use of barre chords and so are not typically considered for capo use.
As you use a capo, you should know where the root is located in every open-position chord you play. Likewise, you should know the notes up the neck, a least on the strings where chord roots lie. For example, when you play G in the open position, you should know that the root, G, is under your finger at the third fret of the sixth string. When you use the same fingering two frets higher with a capo, you should know that the root, which is now at the fifth fret of the sixth string, has changed to A. Positioning a G-chord fingering at the seventh fret is B, eighth fret is C, and so on. Likewise, you should know that the root of an open-position C chord is under your third finger on the fifth string, and know the notes on the fifth string all the way up the neck. Transposing a D-chord fingering is a bit trickier because its root lies on the fourth string, which is a string that guitarists don’t learn the notes on as well as strings six and five; however, you can easily use octaves to trace any note on the fourth string to the sixth string.
Whenever a capo and familiar open-position chord fingerings are in use, always look at the roots in each chord shape to determine their actual notes. For example, if you use the fingerings for G, C, D, and Em with a capo at the second fret, you should know that you’re actually playing the chords:
A (root on sixth string, fifth fret)
D (root on fifth string, fifth fret)
E (root on fourth string, second fret )
F#m (root on sixth string, second fret).
If it helps, first play the chord roots without a capo in their actual locations; then add the capo and rehearse the real notes again before playing the chords. Finally, play the familiar open-position fingerings and keep in mind the actual chords.
Capos are also great for avoiding unnecessary barre chords that result in flat and sharp keys. If a piece of music is in Ab, a key with no open-position chords, rather than play it using barre chords, arrange to play it with a capo using open-position fingerings. Remember from the previous example that placing a capo at the second fret and using chord fingerings from the key of G actually produces the key of A. Move the capo down one fret and this key of A becomes Ab. Move it up and it becomes A#, or Bb, and so on.
Refer to the following handy chart to get to know your options when using a capo to play the three main chords in the key of C. The chord names in parentheses reference the forms that you use in each position, but the actual chords remain C, F, and G throughout.
| Chord Fingerings | Capo Placement |
|---|---|
| C fingerings (C F G) | No capo |
| A fingerings (A D E) | Capo 3 |
| G fingerings (G C D) | Capo 5 |
| E fingerings (E A B) | Capo 8 |
| D fingerings (D G A) | Capo 10 |
Notice that the fingerings from position to position follow the order of the CAGED system. All keys connect positions in this order C, A, G, E, D, C, A, G, and so on — they just start at different points in the loop. In other words, if you start off in the key of A, the next position is based on G-chord fingerings, then E, D, and C as you move up the neck with the capo. If you start out in the key of E, the next position is based on D, and so on. You know your capo is in the right position when the chord root notes match the chords you’re intending to play.