An interval timer that is constructed of a polygonal shaped housing which has a time display screen and a pressure activating button within one surface of the housing and another surface of the housing includes a mode selection switch, time increment button and second time increment button. With the mode selection switch in the set position the first time increment button and second time increment button can be operated to produce a selected time value such as in minutes and in seconds to be displayed within the time display screen. Movement of the mode selection switch to a usage position and pressing of the pressable activating button will result in the selected preset time interval to count down a second at a time (or other minimum time increment) to eventually reach zero.