Advantages of Using Calibration Weights
Balance Calibration Weights
Ensure accurate and reliable results by monitoring the performance of your weighing equipment using calibration weights. Routine balance testing is required by standards such as GMP and ISO 9001, and documented proof is often requested during audits.
Calibration Certificate Ensures Traceability
Using calibrated weights is the only way to ensure traceability and obtain accurate and reliable results. Our accredited mass calibration laboratories meet or exceed ISO/IEC 17025 standards.
Protection and Longevity
To protect the integrity of the weight and ensure a long lifetime, all calibration weights are supplied in a robust, easy-to-clean plastic container. Approved materials, including foam inserts, make them a durable solution.
Design and Construction
Our calibration weights are made from premium austenitic steel, ensuring high resistance to corrosion. Monobloc calibration weights are designed for long-term stability, and weights with an internal cavity can be adjusted without the need for specialized equipment.
Expertly Crafted
Our unique manufacturing process involves traditional mechanical polishing, final stage electrolytic polishing, fully automated cleaning, and final calibration using state-of-the-art mass comparators.
Stable Performance
Our proprietary electrolytic polishing provides a surface that is far smoother than using mechanical polishing. Thanks to the enhanced properties of the passive oxide film that is created on the calibration weight, long-term stability is assured.
CarePac Weight Sets
A CarePac contains two carefully selected weights for testing at the capacity of your balance and at 5% of its capacity - all that you need for safe and accurate weighing processes in between balance calibrations.
Useful Related Links
How to Select the Correct Calibration Weight
Take advantage of our free GWP® Recommendation service to ensure you select the right test weight in the correct weight class to meet your individual accuracy requirements.
Accessories for Calibrated Weights
Handle your calibration weights like a professional with ergonomic tweezers, weight forks, clean-room gloves, and cleaning cloths.
Weight Calibration Services
In our global network of accredited laboratories, your calibration weights are expertly cleaned, calibrated, and adjusted, and returned to you promptly. The results are documented in the weight calibration certificate.
Do You Want Your Balance to Perform at Its Best? Get It Serviced by the Market Leader
Do You Want Your Balance to Perform at Its Best? Get It Serviced by the Market Leader
Calibration Weights - Everything You Need to Know
What are calibration weights?
Calibration weights are standardized masses used to verify and calibrate scales and balances in various settings, such as laboratories, manufacturing, and quality control. They are essential for ensuring the accuracy and precision of weighing instruments. Calibration weights come in various sizes and tolerances, and they are made from materials that resist wear and corrosion, such as stainless steel or brass.
Using calibration weights involves placing them on the scale or balance to compare the displayed weight against the known weight of the calibration weight. If there is a discrepancy, the scale can be adjusted to ensure accurate measurements in future uses. Calibration weights are typically classified according to their accuracy, with higher classes indicating lower permissible errors.
What is the difference between calibrated weights and test weights?
Calibrated weights and test weights are two expressions for the same thing. Calibration weights and test weights comply with OIML and ASTM guidelines and can be purchased with or without a calibration certificate.
What is the difference between calibration weights for balances and industrial scales?
While there are different types of weight construction, the main difference between balance calibration weights and scale calibration weights is the nominal weight value. In the laboratory, weighing instruments are often referred to as balances. For such applications, METTLER TOLEDO’s weight portfolio includes balance calibration weights from 0.05 mg (50 µg) up to 50 kg. In industry, weighing instruments are often referred to as scales. For these applications, we offer weights for scale calibration from 1 kg up to 5 tons.
How to calibrate an industrial scale and which scale calibration weights I need?
If you are unsure which calibration weights you need, our free GWP® Recommendation service helps you select the right weights for your application and process accuracy requirements. For a more comprehensive assessment of your needs, our GWP® Verification service provides you with a full routine testing and calibration schedule, including the test type, test frequency, calibration weights, and weight class according to your precise needs.
Contact your local METTLER TOLEDO representative for a free GWP® Recommendation.
Read more about our GWP® Verification service here:
Weighing Devices - Verifying and Maintaining Accuracy Over Time
What are the OIML and ASTM calibration weights classes?
OIML single calibrated weights have classes E1, E2, F1, F2, and M1. ASTM single calibrated weights have classes 1 to 4.
Is it possible to purchase single calibration weights without a calibration certificate?
Yes, single calibration weights can be purchased with or without a calibration certificate. However, if it is necessary for you to be able to prove traceability, you should always purchase balance calibration weights and scale calibration weights with a calibration certificate.
Do I need to buy a full set of calibrated weights?
To test your balance or scale, only two calibrated weights are required. We recommend using one calibrated weight equivalent to the capacity of your weighing instrument and a second calibrated weight equivalent to around 5% of the capacity. You may wish to use a third weight to test your balance around a specific weight value. You can purchase our calibrated weights separately, or our CarePacs offer a cost-effective solution. Each CarePac contains two selected weights and weight handling tools appropriate to the weight value together in one convenient easy-clean plastic box. However, if you have many balances or scales with different capacities, a full set of calibrated weights may be the more cost-effective option.
How should I handle and store calibration weights? Are there any guidelines for maintaining the integrity of calibration weights?
Spheres are used because the volume can be determined according to the definition of volume by a length measurement. Silicon (Si) spheres have the same homogenous atomic structure as a perfect diamond without voids or dislocations, so the density is more accurate than other materials. This is why a silicon sphere with a homogenous atomic structure serves as a reference for specialized volume measurement.
There are some golden rules for handling calibration weights for scales and balances that also apply to all knob, sheet and wire weights:
- Store in the container provided
- Keep clean
- Acclimatize before use
- Used dedicated tools for handling
- Never touch with bare hands
What is the difference between a monobloc calibration weight and a calibration weight with an adjusting cavity?
Monobloc calibration weights are made in one solid piece whereas a calibration weight with an adjusting cavity has a top that can be removed to reveal the cavity within the body of the weight. During the weight calibration process, minor adjustments can be made to the overall weight value by adding or removing special material. This should only be carried out by accredited calibration laboratories.
Which calibration weights classes offers monobloc weights and which classes have weights with adjusting cavity?
| Weight Class | E1 | E2 | F1 | F2 | M1 |
| Cavity | ✓ | ✓ | ✓ | ||
| Monobloc | ✓ | ✓ | ✓ |
METTLER TOLEDO offer monobloc calibration weights as well as calibration weights with an adjusting cavity. However, the construction depends on the weight class as can be seen in the table above.
Are the milligram calibration weights (mg) sheet weights or wire weights?
| Weight Class | E1 | E2 | F1 | F2 | M1 |
| Sheet | ✓ | ✓ | ✓ | ||
| Wire | ✓ | ✓ | ✓ |
METTLER TOLEDO offers both sheet and wire milligram calibrated weights. However, the shape depends on the weight class as can be seen in the table below. In the higher weight classes, E1 and E2, only wire weights are available. This is because their smaller surface area, in comparison to sheet weights, makes them less susceptible to the effects of air buoyancy and the influences of air drafts. Hence, their higher level of accuracy.
Do I have to calibrate my calibration weights?
Calibration of weights on a regular basis is essential if accuracy, repeatability, and traceability are important to you. Scale calibration weights and balance calibration weights will need to be sent to a special service provider to be calibrated against weights of a higher weight class. You may find it useful to have a second set of calibration weights so that you can continue to test the performance of your balances and scales while the other set is being calibrated.
What materials are commonly used for calibration weights, and how do they affect accuracy?
Calibration weights are commonly made from materials such as stainless steel and brass. Stainless steel is preferred for its durability and resistance to corrosion, which helps maintain accuracy over time. The choice of material can affect the weight's density and stability, impacting measurement precision and reliability.
How do you calibrate a digital scale without weights?
Theoretically, any scale needs a weight to calibrate it and assure highly accurate weighing. If high accuracy is not required, METTLER TOLEDO CalFree can be used to calibrate the scale by using the plant values of load cell and terminal to calibrate. This enables fast and easy calibration to a certain level of accuracy. Additionally, for tank scales RapidCal can be used to calibrate. This is a force calibration method that uses hydraulics to pull down on a tank to calibrate it, rather than using test weights. For a floor scale, typically weights will need to be used.
How often do you need to re-calibrate your weights?
Depending on how often the weights are in use, weights should be re-calibrated every 1-2 years. METTLER TOLEDO has its own calibration laboratories around the world. Contact local representative.
How do environmental factors influence the performance of test weights during calibration?
Environmental factors such as temperature, humidity, and air pressure can influence the performance of test weights. For example, changes in temperature can affect the weight's dimensions and density, while humidity can lead to moisture accumulation on the weight's surface, impacting measurement accuracy. It is important to perform calibrations in controlled environments to minimize these effects.
What is the importance of traceability in calibration weights and how does it relate to quality standards?
Traceability in calibration weights refers to the ability to link the measurements of weights to national or international standards through a documented chain of comparisons. This is important for ensuring the accuracy and reliability of measurements. Traceable weights meet quality standards and regulatory requirements, providing confidence in the calibration process and its results.