Depending on the environment the instrument is being used in, different levels of calibration will be required. The range in which an instrument is configured is decided in accordance with legal requirements and a companies own policy. A company's policy is naturally made in house albeit guided by guidelines of best practice. Legal requirements vary from one area to the next. Because of this companies will hire expert calibration technicians where they do not have their own in-house calibration specialist.

The calibration process typically involves the use of specialized test equipment. Some instrument manufacturers supply testing and calibration kits with their instruments so that the end user can carry out their own calibration. But where accuracy needs to be ensured an expert calibration service will be employed. The equipment they utilize covers a far broader range of testing and calibration possibilities than the generic equipment supplied by manufacturers.

A calibration expert not only brings with them a wide array of tools and equipment but also a great wealth of experience. This allows them to problem solve and error check rapidly and efficiently where an inexperienced employee could wrestle with the trial and error nature of the process for far longer. A calibration technician can also provide reports and recommendations; identify potential areas of improvement and highlight possible performance issues. The technician must be able to investigate and troubleshoot issues affecting accuracy, especially where the cause is completely unknown.

Routine maintenance is the usual reason for calibration but a number of other factors also call for calibration. These could include the manufacturing of a new instrument or a new installation. Emergency maintenance, where an instrument has malfunctioned or been damaged also call for calibration. Where certain changes in environmental conditions occur users may find that readings are questionable. In this circumstance the instrument will be recalibrated to ensure no further misreadings. A sudden change in air pressure, sudden shocks, water damage, gas leaks, corrosion are all examples of environmental changes that might call for recalibration.

In the calibration process itself a measurement standard must be established. How that standard is established will depend on the tolerances of the particular equipment being calibrated. Points of calibration must also be recorded. A lack of occurrence being measured can be used as the zero point for these readings. Industry standards and measurement guidelines established by manufacturers also help to define the measurement standards.

Specialist Industries and businesses are not the only entities that benefit from regular calibration. Where services such as gas, water or electricity have improperly calibrated meters, incomes can be affected for homes, ordinary businesses and municipalities.