The requirements for an extensometer are determined primarily by the characteristics of the material to be tested. Having said this, the right choice of extensometer cannot be limited to the basic material characteristics such as specimen dimensions, stiffness, strength and plasticity alone. It also is necessary to decide whether an extensometer can be connected directly to the specimen without influencing the load measurement or mechanically damaging the specimen itself.
In materials and component testing the range of applications where extensometers are used is extremely diverse. As a result, the technical requirements for these devices are multifaceted, which means that there is no single device which satisfies all needs.