CMC stands for calibration and measurement capability: the smallest uncertainty a lab can achieve for a stated measurement under normal operating conditions, on a near-ideal item. CMCs appear on an accredited lab's scope of accreditation and in the international database of NMI capabilities. A certificate never reports an uncertainty smaller than the CMC, and usually reports more, because real items add their own resolution, stability and repeatability.
Our CMC at 1 kg is 0.05 mg, but with that customer's dented weight we can't get anywhere near it.
Shopping for a cal lab, compare CMCs on the scope; a cheap lab whose CMC is bigger than your tolerance is no bargain.
Also heard as
- calibration and measurement capability
- best measurement capability
- BMC
Related terms
ISO 17025
The international standard setting the competence requirements for testing and calibration laboratories.
Expanded uncertainty
Combined standard uncertainty multiplied by a coverage factor to give an interval with a stated coverage probability.
NMI
National metrology institute, the body that realizes a country's measurement units at the top of its traceability chain.
Uncertainty budget
A table listing every uncertainty source in a measurement with its size, distribution, divisor and contribution to the total.