The best standard an organization holds for a quantity, reserved for calibrating its other standards and kept at the top of the lab's own hierarchy. It is calibrated externally, often by a national metrology institute or a higher-tier accredited lab, handled minimally and stored under controlled conditions to protect its stability. Using it for daily jobs wears it out and defeats its purpose, which is why working standards exist.
Don't use the reference standard mass set on the shop scales, that's what the working set is for.
Also heard as
- lab reference
- master
- reference
Do not mix it up with
- Working standard: A working standard does the daily calibrations; the reference standard only calibrates the working standards.
Related terms
Working standard
A standard used routinely to calibrate instruments, itself checked against the lab's reference standard.
Primary standard
A standard that gets its value straight from the unit definition, not from calibration against another standard.
Calibration hierarchy
The ranked levels of standards, from primary realizations down to working instruments, through which values flow.
Transfer standard
A stable, portable standard used to carry a value from one lab or standard to another for comparison.
Check standard
A stable item measured regularly to confirm a measurement process still behaves as it did when characterized.