Measurement uncertainty impacts your bottom line. Small weighing inaccuracies can lead to material waste, inconsistent quality, and unnecessary production costs. This guide explains how a structured approach to selecting, calibrating and testing scales can reduce these risks and improve process consistency. With Good Weighing Practice™ (GWP™), METTLER TOLEDO provides a risk-based approach to selecting the right scale and managing its performance over time. That way, we can help you reduce costs and achieve consistent production performance.
Hidden costs often originate from weighing processes that are not well understood. Managing measurement uncertainty helps uncover opportunities for savings across material usage, production efficiency, equipment investments, and compliance.
Measurement uncertainty quantifies how accurate a measurement is. It tells you how much a measured value can vary from its true value. It can be described as a range or a “confidence band” around the weighing result.
It can be used as a rough synonym for weighing accuracy, as it is the biggest factor influencing accuracy.
Identifying the cost of measurement uncertainty is only the first step. To consistently reduce waste, avoid rework, maintain compliance, and optimize equipment investments, weighing performance must be managed throughout the entire lifecycle of the scale.
METTLER TOLEDO developed the GWP framework to provide a risk-based approach for selecting, installing, calibrating, and routinely testing weighing equipment to ensure it remains fit for purpose. By maintaining the required level of weighing accuracy over time, manufacturers can protect the cost savings achieved through improved weighing performance.
Selecting the right scale is the first opportunity to control costs. A scale that is not accurate enough can create waste, rework, and quality risks, while a scale that exceeds process requirements may result in unnecessary investment.
The GWP Recommendation service and Uncertainty Calculator help determine the weighing accuracy required for your application and quantify the financial impact of measurement uncertainty. This supports data-driven equipment selection that balances investment costs with operational performance.
Even the right scale can deliver poor results if it is not properly installed.
Get your scale installed correctly right from the start and have its accuracy checked with an initial calibration. This helps confirm that your scale meets your requirements on-site and is accurate enough for your needs going forward.
Scale performance can change due to normal use, environmental influences, and wear.
Regular calibration helps confirm that your scale meets your requirements over time and thus stays accurate enough for your needs.
Our GWP Verification streamlines routine testing. It helps ensure you don't test too little or too much by providing the right testing method, frequency, weight, and tolerances. This allows you to control your scale's performance calibrations.
Difference between a test report and a calibration: A test report is a performance check of a balance or scale based on one or more individual test points. It does not, however, determine the measurement uncertainty. Unlike calibration, it is typically not enough to ensure compliance with internal or external quality standards.
Is what you see on your scale really what you get? Is the weight displayed on your scale truly accurate, reliable, and matching your production requirements? Without the right instrument selection and proper calibration over time, unreliable measurements can cause costly errors, waste, and production inconsistencies, problems that are easily preventable.
Our accuracy services, recommended by the GWP standard, help you determine the measurement uncertainty (MU) associated with your instrument selection and weighing operations. By understanding and managing measurement uncertainty, you can improve weighing accuracy, resulting in reliable, accurate, and compliant measurements that support your key business objectives:
Reliable and reproducible production and quality control lead to consistent product quality.
Reduce waste, avoid costly rework, optimize material usage, and prevent wrong equipment purchases. See more details below.
Knowing and documenting your measurement uncertainty supports full regulatory compliance and audit-readiness.
The accuracy of scales is heavily influenced by their environment. Many industrial sites present unique challenges to weighing accuracy. Understanding and addressing these factors is essential for reliable measurement results:
In industries such as cement, mining, and mineral processing, dust can accumulate on scale components and sensors, leading to erratic readings or sensor drift. To counter this, dust-proof and sealed weighing systems are recommended. Regular on-site maintenance and calibration ensure the instruments remain accurate despite these conditions.
Manufacturing plants with heavy machinery often experience vibrations that can interfere with weighing stability and accuracy. Installing vibration-dampening mounts or isolators and performing calibration with machinery running helps capture real-world uncertainty.
Outdoor weighing stations or refrigerated storage areas can experience significant temperature changes, causing mechanical components to expand or contract. Using temperature-compensated scales and calibrating at typical operating temperatures enables consistent accuracy.
It is crucial to be aware of these environmental influences in order to manage them successfully. They need to be considered, measured, and mitigated through proper scale selection, installation, and regular calibration. Performing these helps ensure that the scale’s measurement uncertainty reflects the true accuracy of the weighing process under real-world industrial conditions.
Measurement uncertainty quantifies how accurate a measurement is. It tells you how much a measured value can vary from its true value. Think of it as a plus/minus range or a “confidence band” around every weighing result.
Watch our webinar „Measurement Uncertainty and Minimum Weight” to learn more
Measurement uncertainty of balances and scales can only be determined by an on-site calibration. It’s the only way to find out how accurate the weighing instrument really is, and METTLER TOLEDO Accuracy Calibration Certificate (ACC) enables that.
The ACC offers the absolute or relative measurement uncertainty covering the scale’s entire weighing range. Optionally, you can also receive various annexes as an assessment of the results, if they meet your business or regulatory requirements.
Readability defines the smallest value you can read on a scale, but it doesn’t tell you how accurate that measurement really is. Relying on readability alone can lead to an underestimation of uncertainty, which can cause costly errors or quality issues.
Measurement uncertainty, on the other hand, consider possible errors , giving you a clear picture of how reliable the weighing results are. It is the only way to determine the true accuracy of a scale in its place of use.
Accurate weighing is critical for dosage formulations. A slight deviation in measurement uncertainty can lead to incorrect drug potency, impacting patient safety and causing regulatory non-compliance with Good Manufacturing Practices (GMP) standards.
Portion control in packaging requires particular weighing accuracy to ensure consistent product size and compliant nutritional labeling. Insufficient accuracy may lead to customer dissatisfaction, product recalls, or legal penalties.
Accurate weighing of raw materials affects reaction outcomes and product quality. Measurement uncertainty beyond required limits can result in off-spec batches, increased rework, and failure to meet environmental regulations.
Small quantities of active ingredients need accurate weighing to ensure product efficacy and safety. High measurement uncertainty can cause batch inconsistencies and regulatory challenges.
Weighing accuracy ensures that parts meet strict weight specifications for safety and performance. Non-compliance with these standards can lead to product recalls and liability issues.
To help ensure weighing accuracy, in 2007, METTLER TOLEDO developed Good Weighing Practice (GWP), a globally recognized standard. It is a risk-based, scientific approach aimed at secure selection, calibration, and routine operation of balances and scales.
GWP ensures that weighing instruments deliver trusted and accurate measurements, fit-for-purpose in any workplace or industry. The reliable results support consistent product quality, help reduce costs, and achieve full compliance.