Your UKAS Accredited Calibration Certificate – what does it mean?

When your temperature or humidity device arrives back from Klipspringer’s calibration laboratory, it will accompanied by a certificate. Do you and your team understand the information you are being presented with and how it relates to your instruments?

Using the example below, this blog will guide you through each element of the certificate along with how and where the information is applicable.


A.   The address where the calibration was completed. In this case it was in our UKAS accredited Laboratory. If the calibration had been completed on a customer’s site, their site address would be entered here.
B. The official UKAS mark, detailing 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 demonstrates that the calibration is traceable to the UK’s national standard.
C. The date the calibration certificate was issued.
D. The unique certificate number.
E. The name of the person who approved the calibration result.
F. The due date of the next calibration; this can only be entered if requested in advance by the customer.
G. The signature of E.
H. The name of the person or company requesting the calibration.
I. The address of the person or company requesting the calibration.
J. The unique serial number of the IUT (Instrument Under Test) which has been calibrated.
K. Where the IUT has a detachable probe or sensor etc, this is the unique serial number for this. When this item does not already have a unique number applied, then this will be the serial number of the IUT with the suffix “A” afterwards. Please note, Klipspringer are able to IndeliMark a serial number onto probe handles for permanent and food-safe identification.
L. The description of the IUT. In some cases, this will also detail any damage to the device on arrival to Klipspringer, or where any adjustment has been made after customer authorisation.
M. The date the IUT was received into the laboratory for calibration.
N. The date the IUT was calibrated.
O. The temperature, humidity or pressure (where applicable) within the laboratory when the IUT was calibrated.
P. The range requested for calibration by the customer.
Q. The method and equipment used to carry out calibration of the IUT.
R. Any specific requirements, such as the depth of the probe in the calibration bath.
S. The temperature or humidity tested against.
T. The actual result of the IUT. A figure different to column S shows that the IUT is reading slightly higher or lower and this is the correction factor. E.g. IUT above is reading 40.10°C @ 40.00°C therefore the correction factor is -0.1, The correction factor should be applied when using the IUT, especially where the device is either to be used for monitoring a CCP (Critical Control Point), or where it is used to check the accuracy of other devices which will be used for monitoring CCP’s. If the calibration certificate relates to an in-house calibrator machine (ECMP4, 8 or 12), this will be an average across the ports.
U. This is the uncertainty of measurement of the calibration. Measurements cannot be absolute and even with the most expensive equipment and controlled environments there is always a degree of variation. The uncertainty value printed on the calibration certificate will have taken several factors into consideration, such as repeatability of result, linearity, atmosphere, equipment being used etc. to give a figure which covers all of these variabilities. An uncertainty measurement allows you to have a high level of confidence in your results. For example, @ 40.00°C the certificate states the IUT reads at 40.10°C, with an uncertainty budget of ± 0.13°C, so your results will confidently be between 39.97 and 40.23°C*.
V. This statement details the ‘k factor’, e.g. k=2. The ‘k factor’ is a statistical calculation for how often the uncertainty will be ± 0.13 °C. When k = 2 you would be safe to assume that 95% of the time the device reading will have an uncertainty of ± 0.13 °C.

* We recommend that you incorporate both the correction factor and the uncertainty value into the operation of your device, to ensure the readings reflect the accuracy required. Where your device has only 1 decimal point, then you should round down or up depending on the combined figure, e.g. 0.13 would be ± 0.1 °C.

Klipspringer’s uncertainty budgets are reviewed frequently and against each other when reference instruments return from UKAS calibrations. As our uncertainty values are low, our customers can achieve the best possible result and be confident when using their calibrated equipment.