The tenor sax sounds a ninth lower
The tenor sax is in B♭, like the clarinet, but an octave lower: it sounds a major ninth below what's written. So for a concert C, the player reads a D an octave and a whole step higher. A piece in C major is written in D major.
Why moving up a whole step isn't enough
If you only go up a whole step, the part sits an octave too low on the page, full of ledger lines below the staff. The tool applies the full ninth and moves the part to treble clef, the way saxophonists read it.
Same transposition, other instruments
Bass clarinet and euphonium in treble clef transpose exactly like the tenor sax.
Frequently asked questions
Can I turn a trombone or bassoon part into a tenor sax part?
Yes. Upload the score, pick that part as the original and “Low B♭ · tenor sax” as the target. If it's in bass clef, it's moved to treble clef.
What if I want the tenor part in concert pitch?
Choose “C · no transposition” as the target and the part is written at sounding pitch.