A fixture for evaluating a metal-to-metal seal. A first metal seal surface and a second metal seal surface are brought into initial contact by engagement of a male connection of a first tubular component and a female connection of a second tubular component to form a metal-to-metal seal. A contact pressure regulator is provided to alter the contact load acting in the interfacial region between the first metal seal surface and the second metal seal surface in a predictable manner. An inlet passage is provided to communicate test fluid to an inlet side of the metal-to-metal seal. An outlet passage is provided on an outlet side of the metal-to-metal seal. In accordance with the method, a capacity of the metal-to-metal seal is expressed as the pressure differential required to just induce leakage given a measure of absolute contact load greater than zero.