First, identify the serve’s contact point above your head—you don’t even need a ball to figure this out. Grab a racquet and extend your arm up over your head as though making contact for your serve. Make sure to really feel that extension in your side when you reach up for your serve. That’s it, folks: the minimum required toss height for your serve.
Key word there being minimum, because the next factor to consider is the serve swing itself. Do you have a long or short serve swing? Are you an Andy Roddick, a Maria Sharapova, or a Roger Federer?
Roddick goes from starting to trophy pose, skipping the notable swing motion of Federer, whereas Sharapova is somewhere in between, with enough takeback to justify that it’s a takeback.