The Ultimate Guide to Calibration

All electronic measuring equipment, including electronic scales, thermometers, and noise metres, can “drift” with time, but the reason you should calibrate your meter varies based on the type of equipment and the application it’s used in.

Why Should I Calibrate my Meter?

You may be confident that your measurements are correct if your metres are validated against a known source and have suitable certification. This is especially important if you’re taking measurements to follow a set of standards or laws, because non-calibrated equipment may give you substantially inaccurate results.

How often should a meter be calibrated?

Although it’s common knowledge that meters must be calibrated at some point in order to remain accurate, we’re frequently asked, “How often does my Meter need to be calibrated by a calibration lab?” Answering this question is both simple and difficult, depending on several aspects.

Here’s the simple answer:

The maximum interval between calibrations as advised UKAS:

  • Dose meters – 1 year, although there should be an extended level of testing every other year
  • Sound Level Meters to IEC61672 – 2 years
  • Other Sound Meters (built to older or different standards) – 1 year
  • Calibrators – 1 year
  • Vibration Meters – depending on what type of vibration meter you are wanting to calibrate, we recommend yearly calibrations, but at the end-user’s own risk they may choose to have it calibrated to a maximum 2 years
  • Barometers (as supplied with Castle Class 1 calibrators) – 1 year

All of the figures stated above are guidelines of the maximum interval, and they assume that equipment is in regular use and are supported by good working practice. In non-typical use, such as:

  • in areas with high or low moisture,
  • in extreme temperatures, or
  • where equipment is used irregularly it’s then appropriate to calibrate your equipment more frequently.

The not so easy answer depends entirely on various factors:

  • Instrument specifications and manufacturer’s instructions – What does the manufacturer recommend?
  • Any requirements of the test specification – Does the application specifically define a maximum calibration period?
  • Expected use of the equipment – heavy use or harsh environments should shorten the calibration period.
  • Review of calibration history – The calibration period should be reviewed and changed if necessary; a history of stable results may increase the period.
  • Reference to the maximum period recommended in the table at the back of the LAB23 document depending on the type of equipment used.

There is one further point that you should consider and that is whether you are ever likely to have to rely on your measurements in court in defence of a noise induced hearing loss claim. In this case, all equipment should be calibrated at least annually. You won’t find this point in any UKAS guidance, but is just something we have learned first-hand with our experience of mitigating noise induced hearing loss claims.


As you can see, the general statement that equipment is okay to be calibrated every 2 years largely isn’t true, so you should be aware that this should at very least be reviewed regularly!

And please don’t forget that a proper calibration is not just a few points checked with an acoustic calibrator – we are talking about a full check of the electrical performance of the equipment at multiple points of frequency and level without the microphone fitted, followed by acoustical checks also at multiple frequency and level points, with the microphone included as part of the system – beware ‘cheap’ calibration houses as you will get what you pay for!

Thermometer Calibration

Temperature is a commonly monitored metric in industrial operations. To sense and control process temperatures, a wide range of mechanical and electrical thermometers are utilised. Regular calibration of these thermometers is crucial for guaranteeing consistent product quality and regulatory compliance in various businesses. An example of some of these applications are:

  • in hygiene compliance of food temperature
  • occupational exposure to heat and heat-stress
  • quality control and manufacturing processes


Gas Monitor Calibration

Gas Meters should be calibrated every 180 days.

They are designed to protect workers against the unseen hazards of gaseous substances within workplace environments, they’re commonly employed in mines, pits, and other enclosed locations where gases are present. These usually work at certain PPM levels.

The calibration of these devices is critical. When a device isn’t calibrated, it won’t provide correct data, putting the tester’s safety at risk. When it comes to gas equipment, erroneous readings might be the difference between life and death.

For the majority of gases, Gas Monitor calibration is a low-cost expense with Four-Gas Meters charged at only £67* for traceable calibration certification.

What kinds of instruments do we calibrate?

We calibrate many different kinds of equipment across many industries, if you can’t see your equipment in the list below, call us and we will be able to tell you if we can do it.

  • Air Pressure Meters
  • Anemometers
  • Audiometers
  • EMF Meters
  • Gas Meters
  • Inspection and Test Equipment
  • Light Meters
  • Multi-Function Meters
  • Sampling Pumps
  • Sound Meters
  • Tachometers
  • Temperature Meters
  • Vibration Meters

We occasionally work with external partners for calibrating specific items. If you would like more information on this then please contact us.

What is the price of calibrating of my meter?

The cost of calibrating a meter will depend on exactly which model of meter you have, and to what standard you would like it calibrated. For example, a Class 1 sound meter UKAS calibration will typically cost more than a Class 2 sound meter traceable calibration, just because of the processes involved in completing both types of calibration.

What some people do not know is that we offer different types of calibration level.

Check / Performance Verification – We will make sure that your kit is working as it should be, checking for any minor faults.

Castle Traceable Calibration – As our standard service, all of our traceable calibrations are carried out to national standards, ensuring that your kit is working how it should be.

UKAS – ‘United Kingdom Accreditation Service’ is an acronym for ‘United Kingdom Accreditation Service.’ It is the United Kingdom’s sole national organisation with legal jurisdiction to certify calibration laboratories. A UKAS-accredited company may legally guarantee that their calibration service meets the requirements of the BS EN ISO/IEC 17025:2017 standard. BS EN ISO/IEC 17025:2017 is the internationally recognised standard for laboratory proficiency in “testing and calibration.”

The highest possible calibration standard available in the UK.



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