Guide
How to transpose for B♭ and E♭ instruments
Hand a trumpet player the piano part and the band will sound a tone apart. Trumpets, clarinets, saxophones and horns are transposing instruments: the note they read is not the note that sounds. Here's how to write their parts correctly.
Why some instruments transpose
When a trumpet player reads C, the instrument sounds B♭. That's why it's called a trumpet in B♭. The name of the instrument tells you which concert note sounds when the player reads a written C.
1. Find the interval for the instrument
| Instrument | Written C sounds | Write the part |
|---|---|---|
| Trumpet, clarinet, soprano sax in B♭ | B♭ | a major second (2 semitones) higher |
| Tenor sax in B♭ | B♭ an octave lower | a major ninth (14 semitones) higher |
| Alto sax in E♭ | E♭ | a major sixth (9 semitones) higher |
| Baritone sax in E♭ | E♭ an octave lower | an octave and a major sixth higher |
| Horn in F | F | a perfect fifth (7 semitones) higher |
| Guitar, bass guitar | C an octave lower | an octave higher |
2. Transpose the key signature
Move the key by the same interval:
- Concert B♭ major → trumpet in C major, alto sax in G major.
- Concert E♭ major → trumpet in F major, alto sax in C major.
- Concert C major → trumpet in D major, alto sax in A major, horn in G major.
This is why bands like flat keys: they become easy keys for B♭ and E♭ players.
3. Transpose every note by the interval
Move each note up by the interval from step 1, keeping the letter names in step. For a major second up: C becomes D, E becomes F♯, B♭ becomes C. Accidentals change with the key: a concert F♯ in C major becomes a G♯ for the trumpet.
4. Check the range of the written part
After transposing, check that the part sits where the player is comfortable. A trumpet part written above G5 is hard for most amateurs. The instrument range checker does this for you and shows the written notes.
5. Label the part
Write "Trumpet in B♭" or "Alto Sax in E♭" at the top, so nobody plays it from the wrong page.
Common mistakes
- Transposing down instead of up. The part goes up because the instrument sounds lower.
- Forgetting the key change in the middle of a medley. Every key change in the score needs a new key signature in every transposed part.
- Using the wrong enharmonic. Write in the key: in D major it's F♯, not G♭.
Medley Writer prints every part already transposed, including the key signatures at each transition.
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