A clamping force measuring instrument for a radial clamping device having at least one force sensor for detecting a clamping force of the clamping device and an evaluation device for evaluating sensor data of the force sensor. The clamping force measuring instrument is embodied as a modular clamping force measuring instrument, having an evaluation module a sensor module. The sensor module includes at least one measurement surface and the force sensor. The evaluation module has a radio interface, a memory and/or a display device. The sensor module and the evaluation module are configured for coupling to one another by a coupling device and each has a data connection device. The data connection devices are connected to one another to produce a data connection in the event of the sensor module being coupled to the evaluation module.