Key Pointers – OIML R111 Scale Calibration Weights

• OIML R111 is the international standard for scale calibration weights

• Defines accuracy classes: E1, E2, F1, F2, M1

• Ensures strict tolerance, density, and magnetic limits

• Certified weights provide accurate and repeatable measurements

• Mandatory for ISO/IEC 17025, NABL, GMP & legal metrology compliance

• Includes calibration & manufacturing certificates

Accurate weighing is the backbone of quality control, trade, research, and regulatory compliance across industries. Whether it’s a laboratory balance, an industrial scale, or a commercial weighing system, accuracy depends heavily on the quality of scale calibration weights  used for verification and calibration. To ensure global uniformity and traceability, calibration weights must comply with internationally recognized standards—most notably OIML R111.

In this blog, Masse Präzise explains what OIML R111 standards are, why compliance matters, and how certified scale calibration weights ensure long-term accuracy and reliability.

What Are Scale Calibration Weights?

Scale calibration weights are precision-manufactured reference masses used to test, calibrate, and verify weighing instruments. These weights help confirm that a scale provides accurate readings within defined tolerances.

Calibration weights are widely used in:

• Calibration and testing laboratories

• Pharmaceutical and chemical industries

• Manufacturing and quality control units

• Legal metrology and inspection agencies

• Research institutions

Without certified calibration weights, weighing results can drift over time, leading to compliance risks, financial losses, and compromised product quality.

Understanding OIML R111 Standard

OIML R111 is an international recommendation issued by the International Organization of Legal Metrology (OIML). It defines the metrological and technical requirements for calibration weights used in weighing instruments.

OIML R111 Covers:

• Accuracy classes (E1, E2, F1, F2, M1, M2, M3)

• Permissible tolerances

• Material requirements

• Density and magnetic susceptibility limits

• Design and surface finish

• Marking, certification, and traceability

Compliance with OIML R111-1:2004 ensures that scale calibration weights are globally accepted and suitable for regulated environments.

OIML Weight Classes Explained

OIML R111 defines multiple accuracy classes based on application requirements:

E1 & E2 Class

• Ultra-high precision

• Used in national standards labs and mass comparators

• Extremely tight tolerances

F1 & F2 Class

• High precision

• Used for analytical balances and laboratory calibration

• Common in pharmaceutical and R&D environments

M1 Class

• Industrial and commercial calibration

• Used for scale verification, legal metrology, and quality control

• Most widely used class in industrial applications

At Masse Präzise, scale calibration weights are manufactured across OIML classes from E1 to M1, ensuring suitability for every calibration need.

Why OIML R111 Compliance Is Critical

Using non-certified or non-compliant weights can invalidate calibration results. OIML R111 compliance ensures:

1. Accuracy & Reliability

Certified scale calibration weights meet strict tolerance limits, ensuring consistent and repeatable measurements.

2. Global Acceptance

OIML R111 weights are recognized worldwide, making them suitable for international audits and exports.

3. Regulatory Compliance

Industries governed by ISO, NABL, GMP, and legal metrology regulations require OIML-compliant weights.

4. Traceability

Each compliant weight is traceable to national or international mass standards.

Key Technical Requirements Under OIML R111

Material Selection

OIML R111 specifies materials that offer stability, corrosion resistance, and minimal magnetic interference. High-grade austenitic stainless steel (SS-316) is commonly used for precision classes.

Density Control

Density must fall within defined limits to minimize air buoyancy effects during weighing.

Magnetic Susceptibility

Low magnetic susceptibility ensures accurate results, especially when calibrating electronic balances.

Design & Finish

Knob type, cylindrical, or flat designs are allowed depending on class and application. Surface finish must be smooth and easy to clean.

Calibration Certificates & ISO 17025 Traceability

OIML R111 compliance is incomplete without proper documentation.

Certified scale calibration weights must be supplied with:

• Manufacturing certificate

• Calibration certificate aligned with OIML R111-1:2004

• Traceability as per ISO/IEC 17025:2017

At Masse Präzise, every calibration weight is supplied with full certification, ensuring acceptance in NABL-accredited and ISO-compliant laboratories.

Applications of OIML R111 Scale Calibration Weights

OIML-compliant calibration weights are essential in:

• Calibration laboratories (internal & external)

• Industrial weighing systems

• Pharmaceutical production lines

• Food & chemical processing units

• Legal metrology inspections

• Research and academic institutions

Using the correct OIML class ensures that weighing instruments perform within their intended accuracy range.

Why Choose Masse Präzise for Scale Calibration Weights?

Masse Präzise is a trusted manufacturer of scale calibration weights engineered for precision, durability, and global compliance.

Our Key Strengths:

• Manufacturing as per OIML R111 standards

• Accuracy classes from E1 to M1

• High-grade SS-316 and cast iron options

• Controlled density and magnetic properties

• ISO/IEC 17025 aligned calibration certification

• Custom and application-specific solutions

Our commitment to quality ensures long-term measurement stability and confidence in every calibration process.

Best Practices for Using Calibration Weights

To maintain accuracy and compliance:

• Handle weights with gloves or forceps

• Store weights in protective cases

• Avoid exposure to dust, moisture, and magnetic fields

• Recalibrate weights at defined intervals

• Use the correct OIML class for your scale

Proper handling extends the life and accuracy of scale calibration weights.

Conclusion

OIML R111 standards are the foundation of accurate, traceable, and compliant weighing systems. Using certified scale calibration weights ensures measurement integrity across laboratories, industries, and regulated environments.

With OIML-compliant manufacturing, ISO 17025 traceability, and precision engineering, Masse Präzise delivers calibration weights you can trust—where accuracy is not optional, but essential.