Top Three Tips for Audit-Compliant Calibration Certificates

Managers reviewing calibration certificates

When it comes to calibrating your weighing equipment there is a wide choice of calibration specialists to partner with. It might be tempting to use the cheapest, the closest, or the fastest, but these drivers may leave you unstuck when it comes to your audits. 

The main criteria for any calibration partner should be whether they can produce certificates that are audit compliant. This will save you more money and time in the longer term.

To help you, we asked Malcolm Williams, Global Approvals Manager for his three top tips for audit-compliant calibration certificates:


1: understand what a good calibration certificate looks like

Educating yourself on your auditors’ requirements, and what should be included in a good calibration certificate, will enable you to select the right calibration partner for your business.

When making a shortlist of partners, ask to see a sample of their certificates and check that the following information is included. This is a general best practice list, and some of the points may be device dependent, so check with your chosen partner if any of them are missing:

  • Certificate name
  • Details of the lab that carried out the calibration 
  • Customer details
  • Unique identification code for the calibration certificate 
  • Name and description of the device to be calibrated 
  • Details of the environmental conditions under which the calibration took place
  • Calibration results with respective sign conventions
  • Name, designation, identification, and signature of the person in charge of the tests
  • A statement that specifies these test results are relevant to the specific device
  • Evidence that the measurements are traceable 


In addition to understanding what your calibration certificate should look like, it’s also important to be able to spot common mistakes during the certification process, so that you can work with your calibration provider to rectify them before your certificates are presented to your auditors. 


Here are the six most common certification mistakes spotted by auditors:

  1. Instrument details such as model or serial number are incorrect
  2. Not following UKAS format for UKAS-Accredited certificates
  3. No certificate expiry date
  4. Claiming UKAS when not accredited to do so
  5. Declaring uncertainties beyond the remit of the lab
  6. Not declaring sub-contractor work


2: the devil is in the detail – request precisely what you need 

Communicating precisely what you need from your calibration partner is the first step to ensuring the resulting certificate will pass your audit. When submitting a request for calibration, remember to state which accreditation you require, be that UKAS on non-UKAS. Include a full and accurate description of the assets to be calibrated along with your own decision rule requirements – this means what you consider to be a pass or fail criteria.  

It is important to state whether you want the calibration to be conducted in their laboratory or on-site and providing a previous calibration certificate is useful as a reference – you could also include some notes on whether you were satisfied with the previous certificate you are providing, and what (if anything) you would like to see done differently.


3: analyse the results and action the contents

Once the calibration is complete and you have received the certificate, check the details to make sure they are correct – mistakes can invalidate the traceability of your certificate.

Next, review the statement of compliance with requirements and specifications, this will tell you if your equipment passed or failed. Action these results accordingly with maintenance measures, replacement parts, or even the purchase of a new asset. 

If the asset is reference equipment, use the calibration results and uncertainties to adjust your processes. 

Here’s a quick list of the results you should analyse and where to find the data on your certificate issued by Avery Weigh-Tronix (the location on other providers certificates may vary):

  • As found/as left data – find this on the last page of the certificate
  • Traceability information – this can be found on the first page, at the bottom 
  • Uncertainty results – This will be in the main results table, last column 
  • Correction/error – Main results table, third column


would you like more information?

Maintaining fully calibrated assets is a task not to be taken lightly, for the benefit of your customers, colleagues, and business.
For further support with calibration, call our team on 0845 939 0020.

Avery Weigh-Tronix specialises in providing a comprehensive range of metrology calibration services. All calibrations are expertly performed to exacting standards for accuracy, reliability, and traceability. Our calibration laboratory is accredited by UKAS to ISO/IEC 17025:2017.