What Exactly IS Calibration, Anyway?


Consider a familiar scenario.  You step on the scale to weigh yourself.  It gives you a reading.  You step off and step back on, and it gives you a slightly different reading.  You repeat the process again a third time, and what happens?  You’ve gained 3 pounds in a matter of seconds!  The scale is inaccurate.

Now consider a slightly more serious situation:  You buy a pack of chicken from the grocery store and cook it up for your family.  A day later, you learn that the chicken has been recalled because of improper refrigeration… but not before you and your family have spent an uncomfortable evening in the emergency room!  The cause is determined to be a faulty temperature gage.

Crank it up a notch, and consider a nuclear plant that is closely monitored by equipment to ensure that everything is running properly and safely.  One shudders to imagine the possible implications if the equipment used to monitor that system was giving inaccurate readings. The results could be catastrophic.

The International Vocabulary of Metrology (VIM 2.39) defines the term Calibration as:

 “an operation that, under specified conditions, in a first step, establishes a relation between the quantity values with measurement uncertainties provided by measurement standards and corresponding indications with associated measurement uncertainties and, in a second step, uses this information to establish a relation for obtaining a measurement result from an indication.Calibration.”


Have your eyes glazed over?

Ok, let’s put that in everyman English.  Quite simply, calibration is the process of checking the accuracy of equipment that is used to measure things, and adjusting it when necessary, to ensure that it is accurate within an allowable range.

This is done by comparing the actual measurements (the “unknown”) of a piece of equipment, against a standard (the “known”), which is a measuring device that is predetermined to be accurate within a manufacturer’s set allowable tolerance.

If the measurements fall within the manufacturer’s or customer’s allowable tolerance range, the unit has passed calibration.  If the measurements fall outside of that allowable range, the unit has failed calibration, and must be either adjusted back into the allowable range or rejected.

Calibration is an important step in ensuring accurate data, maintaining safe procedures, and developing quality products.  See, “Why Should I Calibrate My Equipment?” to learn more about how calibration can improve your business… and your bottom line!