If you’re Googling “how to calibrate weighbridge”, here’s the reality: true calibration is a standards-based, traceable procedure—not a quick tweak with a test truck. At SWIA (Sensortronic Weighing & Inspection Australasia) we calibrate and, where required, verify for legal use under Australia’s trade measurement framework, so your readings stand up in audits and compliance with fair trade.
Why professional calibration matters
In Australia, trade weighing is governed by the National Measurement Act and National Trade Measurement Regulations. If a weighbridge is used for trade (buying, selling or charging by weight), it must meet legal requirements and be verified accordingly. DIY checks won’t satisfy regulators or customers.
NMI guidance also sets expectations for weighbridges used for trade, including approved weighing methods (direct weighing, or end-and-end where specifically approved). A compliant installation and verification protect your business, and if you operate a public weighbridge, your public weighbridge licence.
SWIA’s method: step-by-step calibration done right
1) Site preparation & integrity checks
We conduct a visual inspection of the structure, foundations, restraints, load cells, indicators and cabling for signs of mechanical and electrical performance impedance. We also clean and re-grease friction and mechanical adjustment points to maximum longevity. The instrument is powered, warmed and zeroed, and environmental are observed and monitored, because factors such as wind and rain can have a considerable impact on the effectiveness of calibration and testing.
2) Traceable reference standards
Calibration uses traceable loads: verified test weights where practical, or a combination of verified test weights and substitution loads to test to full capacity on larger weighbridges. This is the accepted method for high-capacity instruments and is in-line with NMI National Instrument Test Procedures (NITP) 6.1-6.4.
3) Multi-point loading—up and down
We apply loads across the working range (for example instrument minimum, 25%, 50%, 75%, full capacity) in increasing and decreasing sequences to capture linearity and repeatability. These procedures align with international recommendations for non-automatic weighing instruments that underpin our NMI test procedures here in Australia.
4) Sensitivity & discrimination (change-point) tests
Where applicable, we perform fine-resolution tests (e.g., change-point with small test increments) to confirm the instrument responds correctly to minimal load changes—again following recognised verification practice.
5) Eccentricity/position testing
Loads are positioned at different points on the deck to ensure accuracy across the entire platform, not just at the centre. This guards against structural or load-cell bias and forms part of standard NMI verification philosophy.
6) Adjustment, sealing & documentation
If adjustment is needed, we make controlled corrections, then re-test. We issue a calibration certificate detailing results and traceability, and for trade use we can complete NMI verification as an NMI-licensed service provider, so your weighbridge is lawful for trade.
Legal-for-trade: what it means in practice
- Approved methods: Direct weighing is preferred; end-and-end is allowed only where the weighbridge is approved for that method by NMI.
- Verification know-how: NMI’s own training covers substitution loads, change-point testing and general weighbridge requirements—the same techniques our technicians use on site.
- Public weighbridge obligations: Licences and operating requirements sit in the national trade measurement laws and regulations.
How often should a weighbridge be calibrated?
Intervals depend on usage, environment, vibration, temperature swing and any repairs or component changes. Many sites benefit from a 6 monthly preventative maintenance (Inspection) service and an annual calibration and re-verification service, with interim checks or re-verifications after repairs or incidents. If your weighbridge shows drift or fails daily checks, withdraw it from use and arrange a service—NMI guidance expects non-compliant instruments to be rectified before trade use resumes.
Business benefits of doing it properly
- Accuracy you can prove – Traceable results that stand up to customer scrutiny and audits.
- Compliance & confidence – Verification to legal standards for trade use, including special methods where approved.
- Less downtime – Routine preventative maintenance and verification schedule minimises downtime and unplanned disruption.
- Better profitability – Reliable weights reduce product give-away, claims and rework.
Why SWIA
SWIA specialises in installation, maintenance, calibration and legal-for-trade verification for weighing systems—including weighbridges—across Australia. We’re industry-recognised and NMI-licensed, and we also help operators navigate public weighbridge licensing and certification.
Bottom line
If you need to know how to calibrate a weighbridge, the safest and most economical answer is: get it calibrated and (if applicable) verified by professionals using traceable standards and recognised procedures. That’s how you protect your business, your customers and your public weighbridge licence.
Book a weighbridge calibration with SWIA and we’ll tailor the procedure to your site, provide full documentation, and keep you compliant and confident on every weigh.
