Measurement equipment gives a number with measurement unit from interaction with work piece. For example if a fastened nut cannot be loosened with 40 Nm torque wrench but can be loosened with a 50 Nm torque wrench, then the torque of the fastened nut is 50 Nm. Another example, when a power supply with built in voltmeter shows 100 V, but the output measured with a reliable external voltmeter shows 110V, it is time to send the power supply for calibration. Any other equipment without measuring function does not need calibration.

The interval until recalibration for most measurement equipment is one year. The basis (e.g. applicable international or national standard) of setting the interval should be available. The equipment manufacturer and calibration vendor should be able to provide this information.

To avoid idle time while waiting for the measurement equipment to come back from calibration, two pieces should similar equipment should be available. When one is sent for calibration, another one can be used.

An independent department (e.g. QA, R&D, finance) monitors the calibration deadline of measurement equipment in production department and test department. The user must not reject the pickup for calibration. The independent department is empowered to initiate work or delivery stop when the measurement equipment is due for calibration. The user may suggest to calibrate the equipment earlier during idle period based on production schedule if the calibration deadline will fall in in a peak period.

Having a master list of measurement equipment also helps in monitoring. The list may be in the sequence of the asset number (a number internally generated and affixed on the equipment) or serial number (although the serial number format is different for different equipment but it can still be arranged in sequence). Example of list:

In spreadsheet, the cell in Alert column is to be formulated with
=IF(TODAY()+10>cell in due date column, "Late", "")
so that it will display the word Late if the delivery is almost due (10 days before) or is already due.

The department owning the measurement equipment engages the calibration vendor. Choose a vendor that
a) is accredited as a calibration lab by local government for the types of equipment it intends to offer service.
b) has a certificate of ISO/IEC 17025.
c) will prompt the user and the monitoring department when the calibration is almost due.
d) will write in the calibration report whether adjustment has been done.
e) offers the fastest delivery.

If the calibration reports show that the model of measurement equipment has not needed adjustment for two consecutive calibration intervals, then the company may redefine period length until next calibration for the same model. For example, if 2010 and 2011 reports show no adjustment, then the company may ask the vendor to print the report and the sticker to be due in 2014 during the calibration in 2012.

Measurement equipment, including newly purchase unit, shall have durable and tamper-proof sticker on it determining its calibration deadline. Wherever a sticker cannot be affixed on the measurement equipment itself, instead the storage case or the storage place is affixed with the sticker.

The user should delicately handle the measurement equipment so that the sticker stays in tact and the equipment is free from conditions that may affect accurate reading (e.g. shock, moisture, sudden change of temperature). Each user is to be given one unit of hand equipment if that hand equipment is frequently needed by more than one user at the same time. Re-calibration may be triggered by the user even before the calibration due date if the equipment has experienced fault conditions or suddenly the reading appears questionable. Delivery stop or product recall may take place in this case. If the reading gives uncertainty without any affecting condition for two times or more before calibration due date, it is recommended for the company to change to another brand of measurement equipment or to redefine recalibration period length.

The department owning the measurement equipment keeps hardcopy calibration certificates. That department shall scan the certificate into softcopy and send to the independent department that monitors calibration deadline. The filing should be in a sequence that enables quick retrieval. When the new calibration certificate comes in, the old hardcopy can be disposed off. Do not keep old and new copy in the same folder to avoid confusion. The softcopy is kept for a number of years based on company product life time. The softcopy file name may follow this format: number used for sequence + due date + Brand + measurement equipment (e.g. 97230150 due 2011-09-09 Fluke multimeter.pdf).

Calibration is not necessary if measurement equipment has verifiable record that it has not been used since the last calibration date.

When using the measurement equipment to carry out inspection on company product, the user is to record the equipment number and its calibration deadline besides the measured result in the inspection report.

Example of equipment that needs calibration and its calibration interval:

If the calibration fee is higher than the price of new equipment, the company can decide to replace it.

For the company to determine that calibration is not necessary for certain measurement equipment (e.g. ruler, vernier caliper), there should be justifiable evidence that the product quality is not affected. It is still recommended to calibrate them, but with prolonged interval (e.g. five years).