Transposition Calculator
Transpose music between any two keys by selecting start key and semitone interval.
See all 12 notes in the new key for singers, guitarists, and arrangers.
Transposition is the process of shifting every note in a piece of music by the same fixed interval — moving a melody or chord progression up or down in pitch while preserving its internal structure. The result sounds identical in character to the original, just higher or lower.
The core formula:
New Note = (Original Note Index + Semitones) mod 12
Where each note is assigned a chromatic index: C=0, C♯/D♭=1, D=2, D♯/E♭=3, E=4, F=5, F♯/G♭=6, G=7, G♯/A♭=8, A=9, A♯/B♭=10, B=11.
The 12-semitone chromatic scale:
| Interval | Semitones |
|---|---|
| Minor 2nd | 1 |
| Major 2nd | 2 |
| Minor 3rd | 3 |
| Major 3rd | 4 |
| Perfect 4th | 5 |
| Tritone | 6 |
| Perfect 5th | 7 |
| Minor 6th | 8 |
| Major 6th | 9 |
| Minor 7th | 10 |
| Major 7th | 11 |
| Octave | 12 |
Worked example: Transpose a song from C major to E major (up a Major 3rd = 4 semitones):
- C (index 0) + 4 = E
- G (index 7) + 4 = B
- F (index 5) + 4 = A
- The chord progression C → F → G → C becomes E → A → B → E
Common real-world uses:
- Singers transpose to match a song to their vocal range
- Guitar capo: A capo on fret 2 transposes all open strings up 2 semitones
- B♭ instruments (trumpet, clarinet): Sound a Major 2nd lower than written — sheet music is transposed up 2 semitones
- E♭ instruments (alto sax): Sound a Major 6th lower — written music is transposed up 9 semitones
Enharmonic equivalents: F♯ and G♭ are the same pitch but are named differently depending on context. This calculator provides the most common enharmonic spelling for each transposed note.