Transposition and the capo

What transposition is

Transposition means moving all the tones (and chords) of a song up or down by the same number of semitones. The melody stays the same, only the key changes. You most often do this to bring a song into a singer's vocal range.

How we transpose chords

You move every chord by the same distance. Transpose a song in C major (C-F-G) up 2 semitones and you get D major (D-G-A). The easiest approach is to move the Roman numerals: I-IV-V stays I-IV-V, only the root changes.

• Up 2 semitones: C → D, F → G, G → A
• Everything else (rhythm, melody, progression) stays unchanged.

The capo: transposition for guitar

A capo is a clamp that presses all strings at a chosen fret, effectively 'moving' the open strings up. With it you play familiar, easy shapes while the song sounds in a higher key. A capo on fret 2 + a C shape sounds like D.

The capo lowers the displayed shapes

Seen the other way around: the capo lets you play a hard key with easy shapes. A song in E♭ major is painful with open shapes; with a capo on fret 1 you play simple D major shapes while it sounds as E♭. So the capo lowers the shape your fingers actually play, while the song sounds in the written key.