Extensometers are instruments used to measure and analyze any changes in the linear dimensions of a sample material. Extensometers can either be contact or non-contact instruments, however, understanding the sample material’s shape, dimensions, and test requirements is necessary when using either type of extensometer. Contact extensometers measurement travel is an engineered and fixed value, which depends upon the range of the transducer, whereas non-contact extensometers will utilize a video camera or laser interferometry system, allowing for a larger field of view than traditional methods. The accuracy of either extensometer relies upon the integrity of the test standards, which can vary depending on the material being tested.