A capo raises the pitch of a guitar by clamping the strings at a chosen fret, acting as a movable nut. It shortens the vibrating length of every string by the same amount, so every chord shape sounds higher by the number of semitones equal to the capo fret.
What does a capo do?
A capo raises the pitch of a guitar by clamping all the strings down at a chosen fret, acting as a movable nut. The nut is the piece at the top of the fretboard that the open strings rest on, and the capo replaces it, further down the neck, so the strings vibrate from the capo instead of from the nut. That shortens the vibrating length of every string by the same amount, which raises the pitch of every string by the same number of semitones: one semitone per fret, so a capo on the 3rd fret raises every string by three semitones. The capo does not change the chord shapes, and that is its whole point. A G shape is still a G shape under your fingers, but it sounds as A major with a capo on the 2nd fret, because every note of the shape has moved up by two semitones. The guitarist plays the easy open shapes, and the capo does the transposing, which is why the capo is used to change key, to make hard keys easy, and to match a singer's voice without relearning the song. The capo calculator works out the new key for any capo position.
How a capo changes the sound
A capo changes the sound in two ways: it raises the pitch, and it changes the tone. The pitch rises by one semitone per fret, so a capo on the 5th fret raises the guitar by a perfect 4th, five semitones, and a capo on the 7th fret raises it by a perfect 5th, seven semitones. The tone changes too, because the strings are shorter, so they sound brighter and thinner, with less bass and more sparkle. A guitar with a capo on the 7th fret sounds almost like a different instrument, bright and jangling, which is why high capo positions are used for shimmering, open sounds. The capo also changes which notes are open and which are fretted. With a capo on the 2nd fret, the open strings are no longer E, A, D, G, B, E, but F#, B, E, A, C#, F#, which are the notes a whole tone higher. The open strings still ring freely, which is why capoed chords sound so open and resonant: the guitar is still using open strings, just at a higher pitch. The G major guitar chord with a capo on the 2nd fret sounds as A major, and the open strings ring as F#, B, E, A, C#, F#, which are the notes of the A major scale.
Worked example — a capo on the 5th fret. Put a capo on the 5th fret and every string rises by five semitones, a perfect 4th. The open strings become A, D, G, C, E, A, which are the notes of the A minor pentatonic scale, and a C shape sounds as F major, because C plus five semitones is F. A G shape sounds as C major, because G plus five semitones is C, and an E shape sounds as A major, because E plus five semitones is A. The key of F major is the key that C shapes make at the 5th fret, and the capo chart shows the full picture.
How to hear what a capo does
Practise by playing the same chord shape at several capo positions, so you hear the pitch rising without the shape changing.
- Play a G shape with no capo, then with a capo on the 2nd, 5th and 7th frets, and name the chord it makes each time: G, A, C and D major.
- Play an open E string, then put a capo on the 1st fret and play it again, and listen for the pitch rising by one semitone, from E to F.
- Play the I–V–vi–IV progression in C major with a capo on the 5th fret, and listen for the key rising to F major.
- Compare the tone of a chord with no capo and the same chord with a capo on the 7th fret, and notice how the capoed version sounds brighter and thinner.
- Use the capo calculator to work out what any shape sounds as at any fret, and check your answer by playing it.
Common mistakes
- Thinking a capo changes the chord shapes — A capo changes the pitch, not the shapes. A G shape is still a G shape under your fingers, and it sounds as A major with a capo on the 2nd fret, because every note has moved up by two semitones, not because the shape has changed.
- Thinking a capo is only for beginners — Professional guitarists use capos constantly, to change key, to match a singer, and to get the bright, open sound of a high capo position. A capo is a tool, not a crutch, and it is used at every level.
- Forgetting that a capo raises every string — A capo raises all six strings by the same amount, so the whole guitar moves up together. If you want to raise only some strings, you need a partial capo, which covers only some of the strings.
Quick reference
This table shows what a capo does to the open strings at each fret, so you can see the pitch rising by one semitone per fret and the open strings changing with it. The open strings are the new nut, and they are the notes that ring freely in every capoed chord, which is why the table is the key to understanding the capo.
| Capo fret | Pitch rise | Open strings become |
|---|---|---|
| No capo | 0 semitones | E – A – D – G – B – E |
| 1st fret | 1 semitone | F – A# – D# – G# – C – F |
| 2nd fret | 2 semitones | F# – B – E – A – C# – F# |
| 3rd fret | 3 semitones | G – C – F – A# – D – G |
| 5th fret | 5 semitones | A – D – G – C – E – A |
| 7th fret | 7 semitones | B – E – A – D – F# – B |
Work through the table by putting a capo on each fret in turn and playing the open strings, listening for the pitch rising and the strings changing. When you can name the open strings at any capo fret without looking, you understand what a capo does, and you can work out any capoed chord from first principles.
Frequently asked questions
What does a capo do on a guitar?
A capo raises the pitch of a guitar by clamping the strings at a chosen fret, acting as a movable nut. It shortens the vibrating length of every string by the same amount, so every chord shape sounds higher by the number of semitones equal to the capo fret.
Does a capo change the key of a song?
Yes. A capo raises the pitch of every string by the same number of semitones, so the whole song moves up by that interval. A song in C major with a capo on the 2nd fret sounds in D major, even though the shapes are still C shapes.
Why do guitarists use a capo?
To change key without changing chord shapes, to make hard keys easy by using open shapes, to match a singer's voice, and to get the bright, open sound of a high capo position. A capo is a transposing tool and a tone tool in one.
Does a capo make the guitar sound different?
Yes. The strings are shorter, so they sound brighter and thinner, with less bass and more sparkle. A guitar with a capo on the 7th fret sounds almost like a different instrument, bright and jangling.
Can a capo be used on other instruments?
Yes, on ukulele, banjo, mandolin and any fretted instrument with a neck. The principle is the same: the capo shortens the strings and raises the pitch, and the shapes stay the same.