Music Transposition Calculator (B♭, E♭ and F instruments ⇄ concert pitch)

Understanding the transposing instrument calculator — concept and principle

This calculator converts a note between concert pitch and the written pitch for transposing instruments such as the B♭ clarinet and trumpet, E♭ alto saxophone, F horn and others. Arrangers, band directors and players use it to write parts and to read concert-pitch charts.

Concert pitch to written: with the default inputs the result is Written A5 (key gains 3 sharps).

How it is calculated

Each instrument sounds a fixed interval away from its written note: B♭ clarinet, trumpet and soprano sax a major 2nd lower; E♭ alto sax a major 6th lower; tenor sax a major 9th lower; F horn a perfect 5th lower, and so on.
Concert → written: move the note up by that interval; written → concert: down.
The note moves by both letter steps and semitones, so the spelling stays correct.
Key-signature change = 7 × semitones − 12 × letter steps (in fifths; + = more sharps).
Frequency of the sounding note uses A4 = 440 Hz.

The principle

Transposing instruments exist so that players can use the same fingerings across a family of instruments in different sizes. An alto saxophone fingering written as C sounds E♭, a major sixth lower. To make it sound a concert C, the part must show the note a major sixth higher, A. Moving by both letter and semitone keeps sensible spellings: concert E♭ becomes written C, not B♯. Shifting every note by the same interval also shifts the key around the circle of fifths, which is why the alto part of a C major piece is written in A major (three sharps).

Worked example

Default inputs: E♭ alto saxophone, concert pitch → written, concert C5.

Interval = major 6th: 5 letter steps, 9 semitones.
Letters: C + 5 steps = A, an octave register later: A5.
Semitones: C5 + 9 = A5, so no accidental: A5; semitones moved 9.
Key change = 7 × 9 − 12 × 5 = 63 − 60 = 3 sharps more.
Sounding frequency of concert C5 = 523.25 Hz.

How to read the result

Write the result note in the instrument's part. For a whole piece, apply the same interval to every note and change the key signature by the number shown: +3 means concert C major becomes A major for alto sax. Check that the written range suits the instrument.

Common mistakes

Moving in the wrong direction; concert to written goes up for these instruments.
Spelling by sound and getting B♯ instead of C.
Forgetting the extra octave for tenor and baritone saxophone.
Assuming horn parts are always in F; older music uses other crooks.

Keep in mind: Some instruments read in different clefs or octaves by convention. Check the conventions for the instrument and the edition you are writing for.

Frequently asked questions

What note does an alto sax play for concert C?

A written A, a major sixth higher.

What is the transposition for B♭ trumpet?

Written notes sound a major second lower, so write a major second higher than concert pitch.

Why are some instruments transposing?

So players can switch between sizes of an instrument family using the same written fingerings.

Sources: J. Rodríguez Alvira, "Reading and Writing Music for Transposing Instruments", teoria.com

Checked 9 Nov 2026. J. Rodríguez Alvira, “Reading and Writing Music for Transposing Instruments”, teoria.com (sounding pitch: clarinet, trumpet and soprano sax in B♭ a major second lower; alto sax a major sixth lower; tenor sax and bass clarinet a major ninth lower; baritone sax an octave and a major sixth lower; horn in F and English horn a perfect fifth lower; clarinet in A a minor third lower; clarinet in E♭ a minor third higher; alto flute a perfect fourth lower).

Your numbers