This document compares and contrasts the uses of will and be going to. Will is used to express predictions, quick decisions, and promises. Be going to is used to express predictions when there is evidence or prior planning, as well as prior plans that have already been made. The present progressive can also indicate prior plans, when used with future time words like tomorrow. Overall, will tends to express spontaneity or firm intent, while be going to implies some degree of planning or forethought.