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Guidance notes on average quantity

The Regulations that cover 'average quantity' control the overall average quantity of a batch of packages and the proportion that falls below the stated nominal quantity through three packers' rules. They also lay down which checks you need to take, what records to keep and how to mark packages. The controls apply to both packers and importers to the EU.

In the guide
The Regulations
What is a package?
The three packers' rules
Required checks
Actual content of packages
Keeping records
Importers and average quantity
Tolerable negative error or 'TNE'

The Regulations
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 variation inherent in the packing process.

What is a package?
A product plus its wrapping becomes a package when they are combined without the purchaser being present, and thus the quantity cannot be altered without the wrapping being opened or changed.

Specifically included in the above definition are knitting yarn and unwrapped bread.

Also caught by the requirements are 'outer containers' containing two or more 'packages' (at least one of which is a package to which these Regulations apply) which:

  • were placed in the outer container without the purchaser being present
  • can't be altered without the package being opened or undergoing a perceptible modification, and
  • the container is intended to be sold or would normally be regarded as appropriate for sale, as the outermost layer of packaging to a consumer

Very small and large items of less than 5g or 5ml, or more than 25kg or 25l are excluded. If you are in doubt about the product you are packing or importing, please contact your local trading standards service for specialist advice.

The three packers' rules
A batch of packages must, at the time of packing, comply with the following rules:

  1. The actual contents of the packages must not be less, on average, than the nominal quantity.
  2. The proportion of packages that are short of the stated quantity by a defined amount (the 'tolerable negative error' or 'TNE') should be less than a specified level (generally no more than 2.5%).
  3. No package should be short by more than twice the TNE.

Required checks
Packers, and importers bringing packages into the EU, have a duty to carry out sufficiently rigorous checks to ensure that all of the three packers' rules are met. This means you should establish a formalised system that:

  • controls the production process
  • sets up effective sampling and checking plans
  • uses 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 on suitable equipment, or
  • checking a statistical sample of the production on 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. If it is 'in use for trade' it has also to comply with its relevant regulations, depending on when it was first put into use. Ask your local trading standards service for advice on specific equipment.

Actual content of packages
The actual content of a package is the total gross weight of the package minus the weight of all the packing. The weight of the packing without the contents is known as the 'tare weight'. Tare weights may be constant for a production, 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 summary, the best guide is to weigh 40 empty packages (or packing material) and determine the average and standard deviation of that group. If the standard deviation of the sample is less than 1/10 TNE for the weight/volume of the contents of the package, it can be assumed to be constant. If it is over 1/10 TNE an allowance for the variation must be made in setting your target quantity for the production run. A regular check of the tare variation should be made to see whether it changes over time or with differing packing materials or suppliers, and the allowance adjusted accordingly. For more detail and advice you should contact your local trading standards service.

Keeping records
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.

Marking needs 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 arranged for you to make up the packages

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.

You may mark the packs with the 'e' mark only on packages over 5g or 5ml and not exceeding 10kg or 10L.

'e' mark

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 European Economic Area and ensure 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 them before applying it.

Importers and average quantity
If you import goods from outside the EEA, 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 provides sufficient evidence to show that the packages comply with the weight requirements.

More detailed guidance on the application of the Regulations can be found on the Department for Business, Innovation and Skills website.

Tolerable negative error or 'TNE'
The following is a table of the TNE values that you should use when complying with the three packers' rules.

Nominal quantity
(g or ml)
Tolerable negative error
5 to 509% of nominal quantity
from 50 to 1004.5g or ml
from 100 to 2004.5% of nominal quantity
from 200 to 3009g or ml
from 300 to 5003% of nominal quantity
from 500 to 1,00015g or ml
from 1,000 to 10,0001.5% of nominal quantity
from 10,000 to 15,000150g or ml
above 15,0001% of nominal quantity

When calculating the TNE as a percentage of the nominal quantity, if the result does not come to an exact 0.1 g or ml then the result is always rounded up to the next 0.1 g or ml.

Please note
This leaflet is not an authoritative interpretation of the law and is intended only for guidance. 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.

Relevant legislation
Weights and Measures (Packaged Goods) Regulations 2006

Last reviewed/updated: June 2013





Aberdeen City Council, Trading Standards Service,
Business Hub 15, Marischal College, Broad Street, Aberdeen, AB10 1AB
Telephone: (01224) 523737 Fax: (01224) 523887
Web: http://www.tradingstandards.gov.uk/Aberdeen/
E-Mail: tradingstandards@aberdeencity.gov.uk
Copyright Aberdeen City Council Trading Standards Service 2012