Voltage measurement method for an on-board network of a vehicle, said on-board network consisting of a high-voltage network and at least one further network (20, 30), - wherein, in the on-board network, (i) the high-voltage network is designed so as to have a voltage measurement device which is electrically connected or able to be connected, via a first line and via a second line, electrically to a positive connection and to a negative connection, respectively, of a high-voltage source and (ii) the further network (20, 30) is designed to have first and second lines (21, 31; 22, 32) which are able to be electrically connected, via contactors (23N, 23P; 33N, 33P), to the first line and to the second line, respectively, of the high-voltage network, and to have a further voltage measurement device (25, 35) which is electrically connected or able to be connected to said first and second lines (21, 31; 22, 32), - characterized in that, in the method, (iii) in a calibration mode with closed contactors (23N, 23P; 33N, 33P), the voltage measurement device (25, 35) of the further network (20, 30) is calibrated against the voltage measurement device of the high-voltage network so as to derive at least one calibration parameter and, (iv) in a measurement mode, voltage measurement in the further network (20, 30) is carried out using the voltage measurement device (25, 35) of the further network (20, 30) and so as to adjust by means of the calibration parameter, wherein, in the calibration mode, a respective calibration parameter is acquired together with one or with a plurality of operating parameters of the high-voltage network and/or of the further network (20, 30), and wherein, in the measurement mode, while adjusting by one or more operating parameters of the high-voltage network and/or of the further network (20, 30), a respective calibration parameter is identified and referred to. - wherein, in the on-board network, (i) the high-voltage network is designed so as to have a voltage measurement device which is electrically connected or able to be connected, via a first line and via a second line, electrically to a positive connection and to a negative connection, respectively, of a high-voltage source and (ii) the further network (20, 30) is designed to have first and second lines (21, 31; 22, 32) which are able to be electrically connected, via contactors (23N, 23P; 33N, 33P), to the first line and to the second line, respectively, of the high-voltage network, and to have a further voltage measurement device (25, 35) which is electrically connected or able to be connected to said first and second lines (21, 31; 22, 32), (i) the high-voltage network is designed so as to have a voltage measurement device which is electrically connected or able to be connected, via a first line and via a second line, electrically to a positive connection and to a negative connection, respectively, of a high-voltage source and (ii) the further network (20, 30) is designed to have first and second lines (21, 31; 22, 32) which are able to be electrically connected, via contactors (23N, 23P; 33N, 33P), to the first line and to the second line, respectively, of the high-voltage network, and to have a further voltage measurement device (25, 35) which is electrically connected or able to be connected to said first and second lines (21, 31; 22, 32), - characterized in that, in the method, (iii) in a calibration mode with closed contactors (23N, 23P; 33N, 33P), the voltage measurement device (25, 35) of the further network (20, 30) is calibrated against the voltage measurement device of the high-voltage network so as to derive at least one calibration parameter and, (iv) in a measurement mode, voltage measurement in the further network (20, 30) is carried out using the voltage measurement device (25, 35) of the further network (20, 30) and so as to adjust by means of the calibration parameter, wherein, (iii) in a calibration mode with closed contactors (23N, 23P; 33N, 33P), the voltage measurement device (25, 35) of the further network (20, 30) is calibrated against the voltage measurement device of the high-voltage network so as to derive at least one calibration parameter and, (iv) in a measurement mode, voltage measurement in the further network (20, 30) is carried out using the voltage measurement device (25, 35) of the further network (20, 30) and so as to adjust by means of the calibration parameter, wherein,