Use tare in selling bulk products
In addition to reliable scales, the reliability of measurement in commerce depends on using the scales correctly. When a product with a price per kilogram is weighed to determine its price, the weight of the packaging material must not be included in the product weight.
The price per kilogram states the price of the product per unit of weight. If the packaging material of the product has not been deducted from the weighing result used to calculate the price, the customer will also pay for the package in accordance with the price of the product per kilogram. This distorts the product prices and the comparability of prices. The error in measurement results due to neglecting the use of tare is much larger than the scales’ largest permitted error.
If desired, sellers may price the packaging material separately, but they cannot charge for the product based on the gross weight.
Weighing bulk products at the service counter
At the service counter, the weight of the packaging material must always be deducted from the weight of the product. The price of the product is determined based on the weight of the product, and the packaging material is not a part of the product.
Example: When weighing cold cuts, deduct the weight of the piece of paper that is weighed with the product from the measurement result before calculating the price. If the sheets of paper are always roughly the same size, their average weight can be used as the weight of the paper included in the weighing due to reasons of hygiene.
Example: If you pack the product in a box, deduct the weight of the box from the weight of the product before calculating the price. If there are boxes of different sizes, specify a tare weight separately for each size. You can set the tare at the service counter either by setting the tare in advance or by using the tare when weighing the product.
In self-service sales, the customers weigh the product by themselves. Self-service sales of bulk products are common in the fruit and vegetable section, for example, or in the sales of prepared salads and loose sweets.
The basic requirement on reporting the price of the product and calculating it based on the net weight is the same as for the sales at the service counter: the weight of the packaging material must always be deducted before determining the price of the product based on the weight.
In a self-service situation, the weight of the packaging material must be deducted from the weight of the product by using a preset tare. The average weight of packaging material, such as a bag or a box, is used as the tare weight. If the product can be packed in boxes or bags of different sizes, set a tare separately for each packaging size or use the tare weight of the heaviest package as the tare weight. Include the box lid in the tare weight.
Setting the tare on scales
In many scales, the tare weight can be set on a product-specific basis. The instructions on how to set the tare can be found in the scales’ operating manual.
The tare weight can be determined by weighing at least 10 pcs of packaging material of the same size for which the tare will be set, and dividing the weighing result with the number of the pieces of packaging material. Depending on the scales’ features, the tare weight can be set either by weighing or by entering the tare weight information for each product.
Measuring Instruments Act 707/2011
Government Decree on Measuring Instruments 471/2014
Government Decree on Non-Automatic Scales 1431/2016
Government Decree on Essential Requirements, Demonstration of Compliance and Specific Technical Requirements of Measuring Instruments 1432/2016
Measuring Instruments Directive 2014/32/EU (MID)
Non-Automatic Weighing Instruments Directive 2014/31/EU (NAWID)
Council Directive 76/211/EEC on the approximation of the laws of the Member States relating to the making-up by weight or by volume of certain prepackaged products
Council Directive 75/107/EEC on the approximation of the laws of the Member States relating to bottles used as measuring containers
Council Directive 80/181/EEC on the approximation of the laws of the Member States relating to units of measurement
Directive 2009/34/EC relating to common provisions for both measuring instruments and methods of metrological control
Website of the European Commission on legal metrology and pre-packaged products
The European Commission’s list on the harmonised standards of the MID
NANDO database Database of the European Commission on notified bodies
OIML International Organization of Legal Metrology
WELMEC (The body for the promotion of European cooperation in legal metrology)