Capo and Key Converter

Paste a chord chart, say where the capo sits, and get the shapes you actually need — plus the capo position that gives you the friendliest chords.

A chord chart is a claim about two different things at once: the key the audience hears and the shapes your left hand makes. Move the capo and one of those changes while the other stays put. Most of the confusion at a rehearsal comes from a chart that only states one of them — someone says “it’s in G” when the guitar is making G shapes at the third fret, which sounds like B flat. This converter keeps the two separate, converts the chord list properly (including slash basses), and then works out which capo position leaves you with the easiest shapes for the key you want.

Why the capo position is the number that matters

A capo does not change the key you are in. It changes the key your hands are in. Put a capo at the second fret and play G shapes, and the room hears A. The chart is right either way, but it is only useful if it tells you which of the two it is naming. Charts written for guitar usually name the shapes; charts written for a band usually name the sound.

Once you accept that, the interesting question stops being “what key is this” and becomes “which capo position gets me the sound with the shapes I can actually play”. A song in B flat can be played with A shapes at fret one, G shapes at fret three, or E shapes at fret six. All three are the same music. The first is easiest to fret, the second keeps the open-string ring a lot of players want, and the third puts you so far up the neck that the guitar starts to sound like a different instrument.

How to use the result

• Read the two key names separately every time. The sounding key is what the singer hears; the shape key is what you fret.
• If the recommended fret surprises you, look at the table before overriding it. The score penalises both awkward shape keys and high capo positions, so a slightly higher fret sometimes wins because it buys you G or A shapes instead of E flat.
• High capo positions cost you more than comfort. Above the fifth fret you lose the low end, the intonation drifts on some guitars, and barre chords above the capo get cramped. The tool flags it rather than pretending it is fine.
• When you transpose to a new key, transpose the bass notes too. A walking bass line built on D/F# becomes something else entirely, and the tool moves both halves of the slash.
• If you are matching a singer, change the sounding key and let the tool pick the fret. If you are matching a guitarist, change the fret and read the new sounding key off the top line.

Questions people ask

• Does a capo change the key?

  No. It changes which shapes produce the key. Capo at fret two plus G shapes sounds A, and the A you hear is the same A whether you make it with A shapes and no capo or G shapes at fret two. The tool always shows both numbers so the distinction cannot trip you up.

• Why does it recommend a fret I did not ask for?

  Because you left “capo to use” on best fit. It scores every fret from zero to six on how friendly the resulting shapes are and how far up the neck you have to go, then picks the winner. Choose an explicit fret in the dropdown if you want a fixed answer.

• Can it read chords like Cmaj7, Dsus4 or Bb/D?

  Yes. Anything after the root letter is carried across untouched, so extensions and suspensions survive the move. Slash chords are split at the slash and each side is transposed independently.

• What if my chart uses no capo at all?

  Leave the capo field at zero. The sounding key and the shape key will be the same, and the tool will still tell you whether moving the capo would give you easier shapes for the same sound.

What this tool does not do. Everything runs in your browser. Nothing is uploaded, nothing is stored, and it works with the internet switched off. It reads the first chord as the chart key unless you override it, so a song that resolves on a different chord will need you to set the key by hand. It also has no opinion about voicings: “friendly shapes” means the open chords most guitarists learn first, not what sounds best for your arrangement. See the site disclaimer. Written by Nico, who builds these tools and writes about writing at WrittenTone.