Your UKAS Accredited Calibration Certificate: What does it mean?

When your equipment is returned to you by Klipspringer’s Calibration Laboratory, it will be accompanied by a certificate. In the interest of maintaining your instrumentation, safeguarding your operation, and securing audit compliance, it is vital that everyone at your site understands the contents of this document.

Using the example below, this blog will guide you through each element of the certificate. It will also explore how and where the information it contains is applicable.

UKAS Calibration

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The address where the calibration was completed. In this case it was in our UKAS accredited laboratory. If the calibration had been completed at the customer’s site, the address of the site would be entered here. 


The official UKAS mark, featuring the laboratory’s accredited number at the bottom.  Details of the schedule for each lab can be obtained from the UKAS website using this code. This symbol also proves that the calibration is traceable to the UK’s national standard. 


The date the UKAS calibration certificate was issued. 


The unique certificate number of the UKAS calibration. 


The name of the person who approved the UKAS calibration result. 


The due date of the next UKAS calibration. Here at Klipspringer, we typically put 12 months in this section. However, some customers ask for a specific due date (e.g. 6 months) and some customers ask for the date to be left off entirely.

The details of the due date will be listed in the contract section at the bottom of the UKAS Calibration Quotation Form. It is important that you share any specific requirements with us before the calibration takes place.  


The signature of E. 


The name of the person or company requesting the UKAS calibration. 


The address of the person or company requesting the UKAS calibration. 


The unique serial number of the IUT (Instrument Under Test) which has been calibrated. 


If the IUT has a detachable part such as a probe or sensor, this is where the unique serial number will be included. If the item does not have a unique serial number, this will be the serial number of the IUT with the suffix ‘A’ included afterwards.

Here at Klipspringer, we are able to IndeliMark serial numbers onto detachable parts for permanent and food-safe identification, so this is another option to explore. 


A description of the IUT. In some cases, this will also detail any damage to the device on arrival at the Klipspringer Laboratory. If any adjustments have been made following customer authorisation, the details of these adjustments will also be included. 


The date the IUT was received into the laboratory for calibration. 


The date the IUT was calibrated. 


The temperature and humidity (where applicable) within the laboratory when the IUT was calibrated. To ensure our calibrations are accurate and can be replicated, our reference equipment is calibrated at an external laboratory.

This calibration takes place within a certain range of temperature and humidity, so any calibrations carried out at our own laboratory need to be done under the same conditions. This is true of any calibration laboratory.


The range requested for calibration by the customer. 


The method and equipment used to carry out the UKAS calibration of the IUT. 


Any specific requirements. A common example of this is a specific temperature point for thermometer calibration. Most laboratories verify a thermometer’s accuracy at three different temperature points, typically -18°C, 0°C, and 100°C. However, some sites will rely on thermometers for very specific applications and will want to verify their equipment to a bespoke measuring point such as 115°C. 


The result of the calibration equipment the IUT is being tested against (typically temperature or humidity). 


The actual result of the IUT. If this figure is different to the result in column S, this indicates the IUT is reading higher or lower than the calibration equipment. The difference is known as the Correction Factor. The IUT above generates a reading of 40.10°C at 40°C, this means the Correction Factor is -0.1°C.  

The Correction Factor needs to be applied whenever your operatives are using the IUT, especially when the device is monitoring a CCP (Critical Control Point) or is being used to check the accuracy of other devices that will monitor a CCP.   

If the calibration certificate relates to the calibration of In-House Calibration Equipment, this figure will be determined by an average across the ports.  


This figure reflects the Uncertainty of Measurement of the Calibration. Even if a calibration is carried out in a controlled environment using high quality equipment, measurements cannot be absolute and will always involve a degree of variation.

The Uncertainty Value printed on your calibration certificate will have factored in variables such as linearity, atmosphere, the equipment being used, and the repeatability of the results.  

The IUT in the example given above generates a reading of 40.1°C at 40°C, so the Correction Factor is -0.1°C. The Uncertainty Value for this measurement is ± 0.13°C, which means the customer will need to factor in a variation of ± 0.13°C. Doing so will allow the customer to be confident of a result that sits between 39.97°C and 40.23°C. 

We recommend that you incorporate the Correction Factor and the Uncertainty Value into your device’s operation to ensure any readings sit within your site’s Acceptance Criteria. The Acceptance Criteria is the accepted range of the Correction Factor for your equipment e.g. 0.5°C.

If you add the Uncertainty Value to the Correction Factor and find that it sits outside your site’s Acceptance Criteria, your equipment will need to be adjusted (if applicable) or replaced.  

If your device only has one decimal point, then you should round down or up depending on the combined figure. For example, ± 0.13°C would be ± 0.1 °C.  

It’s also important that you consider the Uncertainty Values of the laboratory you are working with before arranging your calibration. Here at Klipspringer, our Uncertainty Values are extremely low. This makes it more likely that the results will sit within your site’s Acceptance Criteria.

You can also have total confidence in your equipment, as our Uncertainty Values are reviewed frequently and against each other whenever reference instruments return from UKAS calibrations.  


The ‘k factor’ is a statistical calculation for how often the Uncertainty Value will be what is listed on your calibration certificate e.g. ± 0.13°C. For example, if k = 2, you would be safe to assume that 95% of the time the device reading will have an uncertainty of ± 0.13 °C. 

If you would like further guidance relating to your UKAS certificate, the Klipspringer team would be happy to help. Share your details below to arrange a free consultation.