Mass Calibration Services

Calibration Laboratory Assessment Service (CLAS)Interweigh Systems Inc. provides the highest quality mass calibration service available today. If you use calibration weights to maintain the accuracy of your scales on a regular basis, those weights will eventually deteriorate to the point where they are no longer as accurate as you require. We will verify your weights "as found" and will recalibrate and refurbish your calibration weights using a state-of-the-art laboratory and high quality equipment. For all new and existing weights that need recalibration, we also offer both Traceable and Calibration Certificates. Our mass calibration laboratory and processes are ISO/IEC 17025 compliant and are capable of providing calibrations from 1.0mg to 30.0kg (0.1 lb to 50.0 lb).

ISO/IEC 17025: 2005

What you have to do.

If you need to have your existing weights recalibrated you can take the following steps.
1. Contact us by phone at 1.800.268.3269 or by email at and one of our representatives will call you within a 24 hour period.Download the MCO Form
2. Arrange to deliver your weights to Interweigh Systems Inc. 51 Bentley Street, Markham, Ontario L3R 3L1 Att: Mass Calibration Laboratory. Make sure to enclose a completed Mass Calibration Order form. Click here to download a MCO form.
3. Interweigh can also offer you an efficient pick up and delivery service via our courier business partner. Please call or e-mail us for rates.
4. Once received your weights will be verified, cleaned and recalibrated (if required) within their Class tolerance; and then return shipped within 4 business days for Class F weights and within 10-15 business days for all others.

Our ISO Scope of Accreditation for Mass Calibration

Interweigh’s CAN-P-4E & ISO/IEC 17025:2005 Certificate of Accreditation, Scope of Accreditation and Scope of Calibration & Measurement Capabilities. (These documents are in pdf format and require Acrobat 4.0 or higher.)

Metrology Calibration

Metrological calibration is an absolute necessity for any business that wants to ensure that its industrial scales are both precise and accurate. Precision and accuracy are the two cornerstones of ensuring that commercial transactions are fair and trustworthy. The calibration process is not only necessary for the scales themselves, but for the weights that are used to calibrate those scales. The science of making sure that both scales and weights are precise and accurate is called metrology calibration.

Our Mass Calibration Laboratory

Our Mass Calibration Lab is designed and constructed to meet the recommended environmental and procedural practices as detailed in Measurement Canada's Calibration Procedures for Standards of Mass, document # RP-01FIELD.001. In fact our Laboratory exceeds the requirement by including the elevation of our facility into the calculations for Air Density. Our lab has been accredited for mass calibrations by the Calibration Laboratory Assessment Service (CLAS). Our laboratory is climate controlled with the Temperature at 20 degrees C and the Humidity between 30% and 50%. The Barometric Pressure is measured to 0.05 mm Hg. The lab is fully enclosed with the internal air Hepa-filtered every 20 minutes to reduce any airborne material. The air conditioner's supply and exhaust air is external from the lab's air thus maintaining a clean air environment. Our Mass Calibration Lab is equipped with granite tables for the lab balances, thus reducing vibrations. It also is equipped with a large anti-static mat on the floor to prevent any static electricity effecting the accuracy of the lab balances. Interweigh only uses Certified Class 1 test weights to perform any Class F calibration verifications. These weights are certified by a NVLAP lab and are Traceable to the NIST Standard.

Our Staff

Interweigh's metrology team has been trained in mass calibrations to meet the guidelines of Measurement Canada's Calibration Procedures for Standards of Mass. They also have extensive experience in mass calibrations participating in Weights and Measures Canada's annual re-certification of Interweigh's own field test weights. Only Certified Calibration Technicians are allowed to supply mass calibrations.

The Process

This is accomplished through a hierarchical system where each scale is compared against an external reference, known as a standard. Each standard is then tested against a higher level (more accurate and precise) standard, which is compared against an even higher standard, and so on. In Canada the master document describing how Standards of Mass must be calibrated for use in commercial purposes is Measurement Canada's document RP-01Field. This process of comparison against a standard, and making any necessary adjustments, is commonly referred to as calibration. Detailed records are kept for every standard to ensure traceability, and that the scales used for mass calibrations met clearly identified specifications for both accuracy and precision in all its operating parameters. This collaboration between the government and calibrations laboratories ensures the highest achievable standards possible and guarantees fairness in the marketplace.

Interweigh maintains a complete set of Primary Mass Standards directly traceable to NIST. Our Mass Calibration Services include:

  • Calibration "As Found" and "As Left" deviations from the Nominal Value reported for each weight.
  • Cleaning - Foreign contaminants on weights will be removed
  • Adjustment - If weights are found to be out of tolerance, then the weights that can be adjusted will be (1 piece weights can not be adjusted)
  • Detailed certificate provided with your weights. Click here to view the certificate.
  • Fast turnaround time - Class F Industrial Weights - 3 days from arrival at Calibration Laboratory - All other classes - 5 days from arrival at calibration laboratory.

The following services are available at extra charge:

  • Repair of weights
  • Weight cases, gloves, and other weight handling items
  • Replacement Weights

Contact us today: Toll Free: 1.800.268.3269 or by Email:

The Ownership and Management - Interweigh Systems Inc. 51 Bentley Street, Markham, Ontario, Canada, L3R 3L1
Phone: (416) 491-7001 ~ Toll Free: (800) 268-3269 ~ Fax: (905) 940-1711

Or contact us at one of our five locations: Markham, Mississauga, Woodstock, Montreal and Calgary