Method of calibrating a clock of a chip card circuit, the method comprising the following steps: • at a first time, storing a first time datum of a terminal in the clock, by means of a communication channel between said terminal and the circuit comprising the clock, • at a second time, reading a second time datum of the clock, corresponding to the first time datum incremented by the clock as a function of a first duration between the first time and the second time, the first duration being greater than or equal to three days, • comparing the second time datum with a third time datum corresponding to the incremented first time datum, as a function of the first duration between the first time and the second time, by the terminal or a remote server, • as a function of the result of the comparison, calculating a first calibration datum, characterized by the following: the method further comprises the steps of • storing the first calibration datum in the clock, by means of the communication channel, and, • blocking the communication between the circuit comprising the clock and the terminals external to the chip card, the reading of the second time datum being contactless reading and being carried out by means of the communication channel, the step of storing the first time datum being carried out during a pre-customization phase when the chip card is being manufactured, and the step of reading the second time datum, the step of comparing the second time datum with a third time datum, the step of calculating a first calibration datum, and the step of storing the first calibration datum being carried out during a customization phase when the chip card is being manufactured. • at a first time, storing a first time datum of a terminal in the clock, by means of a communication channel between said terminal and the circuit comprising the clock, • at a second time, reading a second time datum of the clock, corresponding to the first time datum incremented by the clock as a function of a first duration between the first time and the second time, the first duration being greater than or equal to three days, • comparing the second time datum with a third time datum corresponding to the incremented first time datum, as a function of the first duration between the first time and the second time, by the terminal or a remote server, • as a function of the result of the comparison, calculating a first calibration datum, characterized by the following: the method further comprises the steps of • storing the first calibration datum in the clock, by means of the communication channel, and, • blocking the communication between the circuit comprising the clock and the terminals external to the chip card, the reading of the second time datum being contactless reading and being carried out by means of the communication channel, the step of storing the first time datum being carried out during a pre-customization phase when the chip card is being manufactured, and the step of reading the second time datum, the step of comparing the second time datum with a third time datum, the step of calculating a first calibration datum, and the step of storing the first calibration datum being carried out during a customization phase when the chip card is being manufactured. the method further comprises the steps of • storing the first calibration datum in the clock, by means of the communication channel, and, • blocking the communication between the circuit comprising the clock and the terminals external to the chip card, • storing the first calibration datum in the clock, by means of the communication channel, and, • blocking the communication between the circuit comprising the clock and the terminals external to the chip card, the reading of the second time datum being contactless reading and being carried out by means of the communication channel, the step of storing the first time datum being carried out during a pre-customization phase when the chip card is being manufactured, and the step of reading the second time datum, the step of comparing the second time datum with a third time datum, the step of calculating a first calibration datum, and the step of storing the first calibration datum being carried out during a customization phase when the chip card is being manufactured.