🔀 Transposition Calculator
Enter a comma-separated list of notes and choose how many semitones to transpose them up (positive) or down (negative).
Each note moved the same distance
Every note in the list is found in the twelve-note chromatic scale, shifted by the number of semitones you give, and wrapped back into the octave. A large constant is added first so that negative shifts still land on a positive index:
transposed = NOTES[(index + semitones + 1200) mod 12]The defaults, C,E,G moved by +2, return D - F# - A: a C major triad becomes a D major one, because every member keeps its distance from the others. Positive numbers go up, negative down, and ±12 returns exactly what you typed - the tool tracks pitch class, not octave.
Shifts worth remembering
| Job | Enter | Because |
|---|---|---|
| Concert pitch to Bb trumpet or clarinet | +2 | it sounds a tone lower than written |
| Concert pitch to Eb alto sax | +9 | a major 6th lower |
| Concert pitch to F horn | +7 | a perfect 5th lower |
| Chords for a capo on fret 2 | -2 | the capo puts the 2 back |
Frequently asked questions
How do I transpose a song to a different key?
Count the semitones between the two keys and apply that to every chord root. C to D is two, so a C, F, G progression becomes D, G, A. The chord qualities never change - majors stay major, minors stay minor.
How do I transpose a part for a Bb clarinet or trumpet?
Move the concert pitch up two semitones. A concert Bb chord, typed A#,D,F, comes back as C, E, G - which is why a Bb instrument reading C sounds Bb. Going the other way, from the part to concert pitch, use -2.
Can I transpose down instead of up?
Yes, put a minus in front. Singers who need a song lower usually want -1 to -3; -5 is a fourth down and -7 a fifth. The notes come back with sharp names either way, so a downward move can look unfamiliar until you rename it.