Transposing Instruments Explained: Written and Sounding Pitch
A transposing instrument sounds a different pitch from the one on the page. The intervals for common instruments, and how to transpose a part.
On this page
A transposing instrument sounds a different pitch from the one it reads. A B♭ clarinet playing a written C sounds B♭, a major second lower. The instrument’s name is the whole rule: it states the sounding pitch of written C, and every other transposition follows from that single interval. Parts and scores show the pitch the player reads. The audience hears the sounding pitch, which may be a second, a third, a fifth, a sixth or an octave away.
Transposition keeps fingerings consistent across a family
Fingering is the main reason for the convention. Instruments in one family share a fingering system, so one written note uses the same fingers across the family. The clefs and transposition article covers the staff side of the same problem. The B♭ clarinet and the A clarinet are built to be fingered identically, so a written C uses the same fingers on both, and only the sound differs. A saxophonist who moves from alto to tenor finds the same written scale patterns under the same fingers. The written notes already encode the fingering, so the player does not relearn the notation when the size changes.
The horn explains the older half of the convention. Before valves were standard, a horn could change key only by changing its crook, a length of tubing, so the notation had to suit the crook in use. Valve horns can play in any key, but the orchestral horn is normally pitched in F, and the F transposition is a survivor of that system. The part is written a perfect fifth above the sound.
The interval for each instrument
The table reads as one fact per row: the sounding pitch of the note written as C4. The octave is shown because the octave is part of the transposition. The last column applies the same transposition to concert C major, which is the key the written part must show.
| Instrument | Written C4 sounds | Sounding relative to written | Written key for concert C major |
|---|---|---|---|
| Piccolo | C5 | an octave higher | C major, no signature |
| Flute, oboe, bassoon | C4 | as written | C major |
| B♭ clarinet, B♭ trumpet | B♭3 | a major second lower | D major, two sharps |
| A clarinet | A3 | a minor third lower | E♭ major, three flats |
| F horn, English horn | F3 | a perfect fifth lower | G major, one sharp |
| E♭ alto saxophone | E♭3 | a major sixth lower | A major, three sharps |
| B♭ tenor saxophone | B♭2 | a major ninth lower | D major, two sharps |
| Guitar, double bass | C3 | an octave lower | C major, no signature |
Two rows deserve a second look. The B♭ tenor saxophone is a major ninth below written pitch, which is an octave plus a major second, so its written C4 lands an octave below the B♭ clarinet’s B♭3. The letter name is the same and the octave is not. The guitar and double bass are written an octave above their sound, the opposite of the piccolo, which is written an octave below its sound. For the ranges these transpositions produce, instrument ranges for arrangers gives the sounding and usable limits.
A player never reads the concert key. They read the signature on the page, so the reverse conversion is worth knowing. A B♭ clarinet part with four sharps is in E major, and moving that key down a major second gives the concert key, D major. Counting the sharps is the fastest way to check a transposed part: four sharps for a B♭ instrument means the concert key has two. The same rule runs in reverse for writing, since the written key of any concert key is that key moved up by the instrument’s interval.
One written chord, several sounds
The clearest test of transposition is a chord. The page is identical for every instrument, so the same three symbols can mean three different chords:
On a B♭ clarinet that written C major triad sounds B♭3, D4 and F4, a B♭ major triad. On an E♭ alto saxophone it sounds E♭3, G3 and B♭3, an E♭ major triad. On an F horn it sounds F3, A3 and C4, an F major triad. The horn version is the sound to listen for:
Transposing a part in four steps
Transposing a concert part into a transposed part follows the same sequence every time.
- Take the interval from the table for the instrument.
- Move the key signature by that interval. For a B♭ instrument the written key sits a major second above the concert key.
- Move every note by the same interval, so each note keeps its scale degree in the new key.
- Check the octave on its own, against the instrument’s range.
A concert D major scale runs from D4 to D5. Written for a B♭ clarinet, it becomes E major with four sharps, from E4 to E5. The first block is the written part, which is what the player reads. The second block is the sound.
The written version has four sharps and the sounding version has two. Both show the same scale degrees, and the difference between them is exactly the major second the instrument’s name promises. Accidentals move with their notes too. A concert F♯ becomes G♯ in the B♭ part, and G♯ is already one of the four sharps in the written key, so nothing extra is written. Every accidental in the part is the concert accidental moved by the same interval.
Where the convention causes errors
A common error is moving in the wrong direction. A B♭ part is written higher than it sounds, so the written key goes up. A part for concert D major written in C major, which moves the key down instead, sounds B♭ major, the wrong key entirely. Check the direction before the arithmetic.
Octave errors are the second source. A written C4 on a B♭ clarinet sounds B♭3, and the same written C4 on a B♭ tenor saxophone sounds B♭2. Both are correct for their instruments. A part that moves a player into the wrong octave is usually a mistake about the instrument’s transposition, not its key, because the key is easy to check and the octave is not.
The piccolo, guitar and double bass need a separate rule, because their transposition is an octave and their key signature does not change. A concert C major part for the double bass is written in C major with no signature. Only the register moves. This is easy to miss, since the key looks right and the notes look plausible on the staff. Check the register against the instrument’s range, not against the key.
The reverse mistake is just as common. A concert line copied onto a B♭ trumpet part without transposition sounds a major second too low. The player reads every note correctly and still sounds the wrong pitches, so the error never shows up in rehearsal as a wrong note, only as a line that sits in the wrong place in the chord.
A harmonic analysis read straight from a transposed page gives the wrong key for every transposing instrument, because the page shows the written key. Convert to sounding pitch before naming a chord, or analyse from a score in concert pitch.
Practice: check a part against the sound
Take eight bars of a melody you know in concert C major and sing the concert line. Write it out for a B♭ trumpet, which becomes D major with two sharps. Then play the written line on the virtual piano. It should sit a major second higher than the line you sang, note for note.
Repeat the exercise for the E♭ alto saxophone. The written line becomes A major with three sharps, and it should sit a major sixth above the concert line. If the written line is an octave away from where it should be, the error is in the octave, and the key signature is probably correct. Repeat the check until the written line and the concert line differ by the interval in the table and nothing else.
For how transposed woodwind parts combine once they sound, woodwind doubling and balance is the next article to read.
Questions
What does a B♭ clarinet sound when it plays a written C?
It sounds B♭, a major second below the written note. The name of the instrument gives the sounding pitch of its written C, and every other transposition follows from that interval.
Why do parts show a different pitch from the one that sounds?
Instruments in one family share a fingering, so one written note uses the same fingers across the family. Parts show the pitch the player reads, and the instrument's name states how far the sound differs from it.
How do you transpose a concert part for a B♭ instrument?
Raise the key by a major second and move every note up by the same interval. Concert D major becomes E major, with four sharps, for a B♭ clarinet. Then check the octave separately against the instrument's range.
Which common orchestral instruments sound as written?
Flute, oboe, bassoon, viola and cello sound as written. The viola and cello use clefs that move their notes on the staff, but the pitch does not change. Piccolo, guitar and double bass sound an octave away from the written note.
