I'm used to the term gross margin rather than gross profit. You subtract only the cost of sales, also called direct costs, or unit costs . . . those things that go up and down with sales.
Some special industries include amortization as direct costs, like rental business--but that's rare.
And then some people talk about gross profit as gross margin less expenses. In that case, amortization, which is an expense, would count.
Tim
Tim Berry is the president of
Palo Alto Software Inc., which produces the industry's leading business planning software, Business Plan Pro, as well as other popular planning applications for businesses.