1. An instrument that measures the areas of tubular structures or orifices of the body: A calibrator can be used to measure the skin-fold thicknesses in several parts of the body including fat deposits which is used to determine treatments for obesity.

A calibrator is also utilized to measure the diameter of the pelvis in a pregnant woman in order to determine if it is large enough to permit the birth of a child.

2. Materials or substances that are used to make certain things have the same features or levels of quality: Medical laboratories use calibrators to standardize procedures for consistent diagnosing of ailments.