A portable torque tester is a light, easy-to-transport device used to test the accuracy of dial-and-click torque wrenches. However, unlike a torque calibration system, these devices cannot be used to provide wrenches with certification.
While portable torque testers are unable to provide measurements used in the certification process, they are themselves often calibrated using methods approved by the National Institute of Standards and Technology (NIST).
Torque Calibration Systems are used to provide torque wrenches and other torque-related tools with accuracy-affirming certification. However, unlike portable torque testers, they are not as easily transported and thus are not considered to be portable.