Abstract: The invention concerns a method for varying and regulating the speed of a motor powered from a voltage source via a triac, comprising, at least once every alternating voltage interval, the following steps: computing a surface value (SI) corresponding to the current absorbed (I(M)) in a time window (FT) defined between a current switching-on time (ti) and a following current switching-off time (tf); computing an interval of the next triac-blocking time (t′); and controlling the starting of the triac when the blocking time (t′) has elapsed. The invention is useful in particular for household electric and house automation appliances operating at variable speed.