Pick a key and a shift in semitones: get the target key, the complete note mapping for rewriting chords, capo positions for guitarists, and concert-pitch conversions for B♭, E♭, and F instruments.
| Old note | C | C♯ | D | D♯ | E | F | F♯ | G | G♯ | A | A♯ | B |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| New note | D♯ | E | F | F♯ | G | G♯ | A | A♯ | B | C | C♯ | D |
Chord qualities (m, 7, maj7, dim...) carry over unchanged.
To sound in D♯ with open shapes:
Singers: move the key so the melody's highest note sits comfortably - down a whole step (−2) and down a minor third (−3) are the most common fixes for straining choruses. Guitarists: aim for keys whose chords use open shapes (C, G, D, A, E) and cover the rest with a capo. Horn sections: B♭, E♭, and F major are home turf; sharp-heavy concert keys (E, B) force awkward written keys on the horns.
Count the semitone distance between old and new key, then shift every note and chord by that distance. C to E♭ is +3 semitones, so C→E♭, F→A♭, G→B♭, Am→Cm. Chord qualities never change - a minor seventh stays a minor seventh; only the letter names move.
Each capo fret raises everything one semitone while your hands keep playing the same shapes. Playing G-shape chords with a capo at fret 3 sounds in B♭. To play in a target key with open shapes: capo fret = semitones from the shape key up to the target key. The calculator's capo row shows this for the common shape keys.
Transposing instruments read music written in a different key so that fingerings stay consistent across the instrument family. When a B♭ trumpet plays its written C, concert pitch (what you actually hear) is B♭ - a whole step lower. To write for one: notate a major second above concert pitch. E♭ instruments are written a major sixth above; F instruments a perfect fifth above.
The intervals - and therefore the melody's shape and harmony - stay identical; only the absolute pitch changes. Listeners without absolute pitch perceive the same song. The practical constraints are range (does it still fit the singer/instrument?) and idiom (open guitar chords, open strings, and horn registers all favor certain keys).