Just buy a saxophone that’s pre-tuned!

Only kidding.

Every note on a saxophone is a little bit different in terms of intonation.

And that means every note on every different kind of saxophone and even the same type of saxophone from the same brand.

So you could be in tune on one note and completely off for another.

Tuners

You can use a chromatic tuner to see whether your notes are sharp or flat. You could also compare your notes to a piano or a tuning fork.

A ‘guitar’ tuner will work. Just realize that the notes displayed aren’t the names of the notes you’re playing. ‘C’ on alto sax will be displayed as a D# or Eb because the note is a concert Eb. ‘C’ on tenor sax will be displayed as a Bb or A# because that’s what the note is in concert pitch.

Adjustments

You’ll need to adjust the mouthpiece a little bit, depending on temperature, conditions, etc (cold will make your tone flat, heat will make it more sharp), but then listen and adjust and get to know how your saxophone works.

You can adjust the position of the mouthpiece- pushing it in will make the tone rise (become more sharp) and pulling it out will make the tone fall (become more flat).

That can help with any one note, however you don’t want to adjust too much for one note if it makes many other notes go out of tune.

Tip: It’s easier to use your embouchure (especially your lip) to bring the tone down.  So you probably want to err on the side of being a little bit sharp since it’s easier to bring the tone tone.