A method and a system for estimating the state of wear of a cutting tool mounted on a machine tool. The system includes an acquisition module configured to acquire, for a determined duration of machining, values of an operating signal specific to the cutting tool mounted on the machine tool, and a microprocessor configured for calculating current values of a set of wear indicators from the values of the operating signal, and determining the state of wear of the cutting tool as a function of the current values of the set of indicators using a predetermined wear model modeling the state of wear of the cutting tool in function of learning values of the set of wear indicators.