How this calculator works
Transposing a chord moves every note by the same number of semitones, so the chord keeps its shape and only the root changes. Transposing by a key change is the same operation: find the interval from the old tonic to the new one and shift by that distance. Going up a fifth from C to G is seven semitones; going down to G is five semitones, and either way the chord ends on G because the two routes are an octave apart. The page spells the new tones by letter and accidental, so a minor triad stays a minor triad with the correct flats or sharps.
Formula
new root = (old root + semitones) mod 12. For a key change, semitones = (new tonic - old tonic) mod 12 when moving up, or that value minus 12 when moving down. Every chord tone moves with the root, keeping the same intervals.
Worked example
C major transposed up a major second becomes D major: D, F# and A. A minor transposed up a minor third becomes C minor: C, Eb and G. Changing key from C to G with the up direction moves everything seven semitones, so C major becomes G major: G, B and D. Moving down from C to G moves five semitones and lands on the same chord.
Advertisement
Frequently asked questions
Should I transpose up or down?
The same key can be reached by either route, and the chord names are identical. Choose the direction that keeps the part in a comfortable range. Moving down a fifth and up a fourth reach the same pitch class; the octave and the resulting melody notes decide which is easier to sing or play.
What about a guitar capo?
A capo raises the instrument by the number of frets you place it on. To play in a higher key without learning new chords, transpose the chords down by that number of semitones and put the capo on. For example, capo on the second fret with chords written in D sounds in E.
Why does a transposed chord change spelling?
Notes must keep their letter relationships. Transposing C major up a semitone gives a chord that is properly spelled Db, F and Ab rather than C#, F and G#, even though the keys sound the same. Choose the spelling that matches the new key.
Does the chord type ever change?
No. A major triad stays a major triad, and a seventh chord keeps its seventh. Only the root and the letter spellings change. If the transposition puts the chord in an unusual key, the result may have many sharps or flats, which is a spelling issue rather than a different chord.