Recommended Calibration Interval

Q. Does NIST require or recommend specific recalibration intervals for measuring instruments, devices or calibration standards?

A. In general, NIST does not require or recommend any set recalibration interval for measuring instruments, devices, or standards. Specific recalibration intervals depend on a number of factors including:

• Accuracy requirements set by customers

• Requirements set by contract or regulation

• Inherent stability of the specific instrument or device

• Environmental factors that may affect the stability

In the absence of other external requirements for specific intervals, NIST recommends that calibration and measurement laboratories adopt internal measurement assurance programs that include cross-comparisons of primary and secondary measurement standards. Recording and analyzing the resulting data in control charts can be used to characterize the short and long-term behavior of specific devices. This time-dependent behavior can be compared to the accuracy requirements of the particular application to determine an initial recalibration interval. Subsequently, recalibration reports should include "as submitted" and "post calibration" accuracy and precision data to validate and/or refine the interval.

NCSLI has a recommended practice that can help you determine a reasonable recalibration interval based on your own situation: