An instrument for counting duration for differentiated phases, including: plural mechanisms for recording a time duration, each actuatable, for activation and deactivation thereof, by a first controller; a general controller for controlling, from an inactive position in which all the recording mechanisms are deactivated, activation of only one of them, selected by a selector, and for again controlling, at a final moment, deactivation of all the recording mechanisms; a switch configured, during a command for activation of one of the recording mechanisms, to trigger the deactivation of all other recording mechanisms and to save totality of the recorded times, counted on each of the recording mechanisms. The selector is configured to be controlled by a user or/and by a measuring mechanism or/and by a signal to trigger the activation of one of the recording mechanisms.