Capo Calculator
Set the key you need to hear and the fret you want to be on. We work out the shapes you actually finger.
The one thing people get backwards
A capo clamps across the neck and shortens every string at once. Shorter strings mean higher pitch, one semitone per fret. So everything you play moves up — and the shapes you need to finger are correspondingly lower than what the room hears.
That inversion is where it goes wrong. Someone needs a song in B flat, reaches for the capo, and transposes the chart up to B flat as well — ending up a long way from the band. The correct move is to subtract: with a capo on 3, sounding in B flat means playing G shapes.
Set the key you want people to hear, choose a fret, and the shape key updates. Run through the frets and pick the position that leaves you with shapes you can play fluently — usually C, G, D, A or E, because those give you open strings that ring under the chord. That ringing is the whole reason to use a capo instead of barre chords: it is a different sound, not just an easier one.
One caution for a band: a capo is a guitarist's convenience and nobody else's. Keyboards, bass, brass and singers all work in the sounding key. Hand the guitars the shape chart and everyone else the sounding chart, or you will spend the first verse discovering the problem.
Frequently asked questions
Up. A capo shortens every string, so the pitch rises by one semitone per fret. That means the shapes you finger are lower than the key people hear — which is the opposite of what most people guess under pressure.
A. Two frets above G is A. The same arithmetic runs in reverse when you know the key you want: to sound in A with a capo on 2, play G shapes.
Open strings. Playing E, A, D, G and C shapes gives you ringing open strings that closed barre shapes cannot, and those shapes are far easier to play quickly. A capo lets you keep the easy shapes while matching whatever key the singer needs.
The one that leaves you with shapes you can play well. Set the key you need to sound and try each fret — the tool shows the shape key for every position, and the familiar ones (C, G, D, A, E) are usually the right answer.
Only the guitars. A capo changes what a guitarist fingers, not what anyone hears, so keyboards, bass and horns all read the sounding key. Print the sounding chart for them and the shape chart for the guitars.
Yes. The arithmetic is the same on any fretted instrument with standard semitone frets — one fret is one semitone regardless of how the instrument is tuned.
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