Classical utilitarianism is the form of utilitarianism espoused by the founding fathers of utilitarianism, especially Jeremy Bentham. It is generally understood to be a form of total, hedonistic act consequentialism that gives equal intrinsic weight to positive and negative hedonic states.
Further reading
MacAskill, William, Darius Meissner & Richard Yetter Chappell (2021) Elements and types of utilitarianism, Utilitarianism.Net.