Packaged goods – average quantity
An overview of 'average quantity' and what is required of packers or importers of products
This guidance is for England, Scotland and Wales
The 'average-quantity system' covers packaged goods that are sold by weight or volume and applies to both foodstuffs and non-foodstuffs that you would typically find in a supermarket or DIY store.
The Regulations that cover the average-quantity system control the overall average quantity of a batch of packages. They contain the 'three packers' rules', which regulate the proportion of a batch allowed to fall below the declared weight or volume on the container (known as the 'nominal quantity').
The effect of these Regulations is to ensure that 'on average' each package contains the declared weight or volume of goods. They also lay down what checks you need to take, what records to keep and how to mark packages. The controls apply both to packers and to those importing into the European Union (EU).
In the guide
- The law
- What is a package?
- The three packers' rules
- Required checks
- Actual content of packages
- Quantity control systems
- Keeping records
- Importers and average quantity
- Further reading
The Weights and Measures (Packaged Goods) Regulations 2006 apply to packages that are made up without the customer being present, in pre-determined constant quantities, by weight or volume, including most food and non-food items. The purpose of the Regulations is to ensure customer confidence in the stated quantity, whilst recognising and defining acceptable tolerances to the variations in quantity inherent in the packing process. The Regulations do not apply to 'catchweight' items where the quantities within containers vary - for example, prepacked cheese where the price you pay is dependent on the weight of the individual item.
A product plus its container becomes a package when they are combined without the purchaser being present (usually in a manufacturing environment) and thus the quantity cannot be altered without the container being opened or changed.
Very small items of less than 5g or 5ml, or large items of more than 25kg or 25l, are excluded from these Regulations but the quantity still needs to be at least that stated. Also excluded are goods sold by length or number. If you are in doubt about the product you are packing or importing, please contact your local trading standards service for specialist advice.
A batch of packages must, at the time of packing, comply with the following rules:
- the actual contents of the packages must not be less, on average, than the nominal quantity (that declared on the container)
- the proportion of packages that are short of the declared quantity by a defined amount (the 'tolerable negative error' or TNE) should be less than a specified level (generally no more than 2.5%)
- no package should be short by more than twice the TNE
Packers, and importers bringing packages into the EU, have a duty to carry out sufficiently rigorous checks to ensure that all three of the packers' rules are met. This means you should establish a system that:
- is formalised and controls the production process
- sets up effective sampling and checking plans
- stipulates an appropriate target quantity
- controls limits
- uses and maintains appropriate equipment for checking
- trains staff
- keeps appropriate records
You have a duty to ensure the quantity of product in the packages, either by:
- measuring the content of each package using suitable equipment
- checking statistically-selected samples from the production using suitable equipment and keeping records of the results
The equipment used to carry out the checks must be suitable for the use to which it is put. This means that it should have a reasonable degree of sensitivity and accuracy, weighing to 0.2 TNE for the package you are producing, and be suitable for the environment in which it is used. Equipment must be calibrated and accurate and details of any repairs/alterations must be retained. Ask your local trading standards service for advice on specific equipment.
The actual content of a package (the net weight or volume) is the total gross weight of the package (package plus contents) minus the weight of the package. It is common practice when packing liquids to weigh containers instead of measuring using the equation volume = mass divided by density.
The weight of the package without the contents is known as the 'tare weight'. Tare weights may be assumed to be constant if the variation in packaging weight is within acceptable limits, in which case the actual content of the packages is easy to determine by simple subtraction. However, where the tare varies from pack to pack, an allowance must be made for this. In order to avoid destructive testing that involves breaking open packages and weighing or measuring the contents, you should specify to your packaging-material supplier that variability in packaging weight must be such that gross weighing and simple subtraction can be employed.
For more detail and advice on ensuring consistent tare weights you should contact your local trading standards service.
Where the packing process variability (standard deviation) is always less than 0.5 TNE of the product then the average requirement (packers' rule no. 1) is the most critical.
Where variability exceeds 0.5 TNE then target quantity (the amount you set your filling machine to fill each container) must exceed the declared quantity so as to comply with the three packers' rules.
If you test less than 50 items in a production run, then a sampling allowance must be added to the target quantity (that is, increase the fill weight). A production run is the time taken to produce 10,000 packages (with a minimum of one hour and a maximum of one normal day). Different products demand differing levels of checking and testing.
The guidance notes on the GOV.UK website give an example of setting target quantities and action limits.
For more detail and advice you should contact your local trading standards service.
If you are checking packages by statistical sampling, you must make records of the checks you have carried out. These records must show that you have complied with the three packers' rules. It is recommended that, as a minimum, you should record the product, the batch number, the date, the number of packs in the batch, the number checked and the results of the check.
A record must also be made of the corrections and adjustments that the checks have shown to be necessary. The records must be kept for 12 months from the time the packages leave your possession or the shelf life of the product, whichever is the earliest.
Required markings need to be easily legible and visible under normal conditions of presentation. This means taking into consideration use of colour and contrast. Packages must be marked with the following:
- a statement of the nominal quantity. This statement must be in metric and the size of the marking is prescribed - for example, for a 500g pack the marking must be at least 4mm high
- your name and address. Alternatively, you may give the name and address of the person who asked you to make up the packages on his behalf
Whether the visibility requirement is met will be a matter of fact but one way to ensure that markings are visible in normal conditions of presentation is to place the markings on the front, or possibly the top, of the container. If you are packing foodstuffs within the scope of the Food Labelling Regulations 1996, remember that the name of the food and the net quantity (weight or volume) must appear in the same field of vision.
You may mark the packs with the 'e' mark only on packages of at least 5g or 5ml and not exceeding 10kg or 10L.
It must be at least 3mm high, indelible, easily legible and appear in the same field of vision as the statement of quantity. The 'e' mark acts as a metrological passport for goods sold throughout the EU and ensures free movement of the goods. If you want to export goods with the 'e' mark, you may need to notify your local trading standards service first so check with the service before applying it.
If you import goods from outside the EU, you are responsible for ensuring that the packs comply with the three packers' rules and that they are marked correctly. However, you may obtain and keep suitable documents from the actual packer (before the packages leave your possession) that provide sufficient evidence to show that the packages comply with the weight requirements. The person providing the documentation has to be of a suitable status (for example, an accredited test laboratory or national metrology service) and the information it contains should be validated.
More detailed information on the application of the Regulations can be found on the GOV.UK website.
This information is intended for guidance; only the courts can give an authoritative interpretation of the law. Any legislation referred to, while still current, may have been amended from the form in which it was originally enacted. Please contact us for further information.
Last reviewed/updated: June 2014