A portable measuring instrument used to measure various force values or loads. Also known as a dynamometer. There are various classifications, divided into working force-measuring instruments and standard force-measuring instruments according to the object of use. The main indicators for evaluating the accuracy level of a dynamometer are repeatability R and stability Sb. R reflects the changes in data obtained from multiple loading (unloading) during a complete verification process; Sb reflects the difference between the verified data and the last data after a period of time.

Force measuring instruments have various structural forms, but their main part is a curved elastic steel sheet or spiral spring. When an external force deforms the elastic steel sheet or spring, a transmission mechanism such as a lever drives the pointer to rotate. The position where the pointer stops on the dial is the value of the external force.