The baritone sax sounds an octave and a sixth lower
It's in E♭, like the alto sax, but an octave lower: it sounds an octave and a major sixth below what's written. For a concert C, the player reads an A. A piece in C major is written in A major.
From bass clef
The bari part often comes from a tuba, bassoon or double bass line in bass clef. The tool does the full transposition and moves the part to treble clef, the way saxophonists read it.
Frequently asked questions
Is it the same as alto sax?
It looks the same on the page but sounds an octave lower. Choose “Low E♭ · baritone sax” so the octave is right.
Does it work for alto clarinet?
Yes, it's also in E♭ and transposes like the baritone sax.