Weights and measures

If you weigh or measure goods to sell to consumers, the law states that your equipment must be both suitable and accurate.

The law also covers the manufacture and approval of this equipment, and lays down requirements about specific quantities in which certain goods must be sold.

What's covered

Generally the law requires the majority of food, drink and other goods sold to the public to have their quantities indicated for the customer. This includes goods that are weighed or measured at the customer's request or packaged ready for sale. The laws that apply to both the goods and equipment used to measure quantity are quite extensive, variable and technical. There are often legal meanings allocated to specific words and phrases by the laws, which are explained in the In-depth Guides.

Quantities

Nearly all measurable goods must have their quantities stated in metric amounts - for example, kilograms, litres or metres. Note that the pint must be used for draught beer, lager and cider; milk in returnable bottles may also be sold by the pint. Some products may be allowed to be sold by number.

Equivalent 'imperial' quantities - such as pounds, ounces, pints and yards - can be given in addition to the required metric indications, but they must not be more prominent.

Some products have to be sold in particular quantities:

• unwrapped loaves of bread without any weight indication given: 400 g or 800 g, or any other multiple of 400 g
• beer, lager and cider: ¹⁄₃ pint, ¹⁄₂ pint, ²⁄₃ pint, or multiples of ¹⁄₂ pint
• wine: 125 ml, 175 ml, or multiples of 125 ml or 175 ml
• whisky, gin, rum or vodka: 25 ml or 35 ml, or multiples of 25 ml or 35 ml

Labelling

Consumers must be able to see what the quantity is for goods required to be sold by weight or measure. This must be included on the products' labels. Some fruit and vegetables are not included as they can be counted easily through the packaging. See 'Quantities' above for information on the prominence of the quantity information.

Price marking

Non-prepacked goods that are weighed at the request of the customer must have their unit price indicated to the customer by price per kilogram. The price per pound can be given in addition, provided it is not more prominent than the metric price.

Although they are not required to, some traders add the price per 100 g for high-value goods such as cheese and meat to give a more meaningful price indication to consumers.

Some goods traditionally sold in smaller quantities are allowed to be priced in smaller units, where this allows the customer a better indication of the value of the goods. Examples of this are sugar confectionery and chocolate, herbs, spices and coffee; these can be price marked per 100 g.

In larger self-service shops, goods that are sold by weight or measure are required to display an equivalent unit price for goods sold with an indication of quantity - for example, equivalent price per 100 g (or 100 ml). This is to allow consumers to compare the relative values of similar products that are sold in different quantities.

Weighing and measuring equipment

Equipment that is used to weigh or measure goods for consumers must be suitable for the quantity being determined and accurate within specific tolerances.

Equipment used for consumer sales is required to be 'Government stamped'. This refers to markings that show the equipment has been made in accordance with a particular regulation or standard, and that it meets accuracy requirements.

Government stamps generally take the form of a series of stickers attached to the equipment. On older equipment, there could be a lead plug embedded into the equipment, on which is stamped a numbered crown and year.

Information plates on some equipment also give the required details.

Measuring equipment that has tested as inaccurate or no longer conforms with other requirements will have a six-pointed star stamped on or affixed to it. Look out for this if you're buying second-hand equipment.

Construction requirements, measuring capacity and accuracy tolerance requirements also vary with the value of the goods being sold. Equipment used to buy and sell gold, silver, etc has different requirements to that used to sell potatoes.

Here are some examples of weighing and measuring equipment for consumer sales that need to be stamped:

• weighing machines, used for:
  • fruit and vegetables
  • sweets
  • meat and fish
  • postal services
• measures of volume:
  • beer glasses and automatic measuring meters
  • alcoholic spirits measures ('optics') and 'thimble' measures
  • wine glasses and carafes
  • petrol pumps
• length measures:
  • metre measures used for material, fabrics, ribbon, electrical cable, etc
  • flexible tapes, used for carpet and other floor coverings

Inspections

New weighing and measuring equipment intended for determining the quantity of goods sold has to be manufactured to an evaluated and approved type, called a 'type examination certificate' (TEC). This means that the design and construction of the equipment must have been evaluated, approved and certificated by legislation and have the appropriate required markings and details attached to it.

This equipment is then subject to periodic inspection for accuracy and continued conformity by Trading Standards officers who are qualified in weights and measures.

These inspections may be scheduled at intervals, which are determined by the use that the equipment is put to and the likelihood that it may wear and become inaccurate. They could be as frequent as every six months or as far apart as five years.

If weighing and measuring equipment is found to be not of the required accuracy, the inspecting officer may issue instructions to have the equipment adjusted.

For more serious discrepancies, the officer may 'reject' the equipment, thus revoking its qualifying stamp with the six-pointed star (see above). This means that the equipment cannot be used again until it has been repaired to the requirements of the TEC and re-stamped. An officer may also reject equipment that is in use but hasn't been stamped.

Where serious fraud is suspected involving the use of weighing and measuring equipment, it could be seized, followed by possible legal proceedings.