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Weighing equipment in use for trade

Weighing equipment that is used for trading purposes is required to be accurate and appropriate for purpose

This guidance is for England, Scotland and Wales

All weighing equipment in use for trade must be suitable for its intended purpose and be sufficiently accurate. Non-automatic weighing machines are either 'passed as fit for use for trade' by an inspector of weights and measures (a suitably qualified trading standards professional) or an 'approved qualifier'.

If the equipment does not bear the stamp or stickers, it must not be used for trade purposes. It is also an offence to have, or use, seriously incorrect equipment or to alter equipment that is incorrect after it has been stamped. Additionally, weights that are in use for trade in conjunction with weighing equipment must be stamped with the crown stamp. There are a number of checks to ensure scales are always working properly too.

Automatic weighing machines are not normally passed as fit for use for trade but are still required to be suitable for the process and sufficiently accurate. Checks should be carried out to ensure the machine is maintained and accurate.

In the guide

In summary

This guide summarises the main requirements of weights and measures legislation enforced by the trading standards service on weighing equipment in use for trade, and relates to weighing equipment that determines the final quantity of the goods delivered to the customer. The controls over such equipment depend on its type of construction and the use to which it is put. Weighing equipment used during a production process (for example, to check ingredients or as a check scale for customer use only) is not in use for trade provided there is a further final check over a stamped scale.

Non-automatic weighing equipment

Non-automatic weighing equipment used must be accurate and approved for trade use.

Non-automatic weighing instruments (those that require an operator to place and/or remove the items from the scale pan) are either passed as fit for use for trade by an inspector of weights and measures or an approved qualifier (a person who is officially authorised to carry out the same qualification duty of an inspector).

The crown stamp, qualifier's identification stickers, and other markings

The inspector or approved qualifier checks that the equipment is suitable for its intended purpose and that it is sufficiently accurate. Such equipment may bear the crown stamp for existing equipment still in use or, for all new equipment, the European approval stickers shown in this guide.

An example of a crown stamp is shown below:

weights and measures crown mark

Most new designs of electronic scales do not have to be 'stamped' by an inspector. Instead, they will have to bear a green sticker with the letter 'M' on it in black, together with the approved qualifier's identification sticker and other markings, including the mark 'CE'.

weights and measures M mark 

weights and measures mark

Above is the old approved qualifier's identification number. The current approved qualifier's identification number is a plain white label in which the 'notified body' number has been overprinted using a thermal printer, as shown below.

weights and measures mark

These green 'use for trade' stickers and qualification stickers can only be placed on the equipment by an approved qualifier or an inspector.

Similar controls exist for equipment required to be crown stamped.

These markings will be readily visible by external inspection.

Non-automatic weighing equipment that is rejected as fit for trade use

If the equipment does not bear the stamp or stickers, it must not be used for trade purposes. It is also an offence to have or use seriously incorrect equipment, or to alter equipment that is incorrect after it has been stamped.

If an inspector finds equipment that is incorrect, which has a lead seal crown stamp, it may be obliterated by a six-pointed star. The equipment must not be used until repaired and re-stamped.

weights and measures mark

The following illustration shows the same sequence for equipment having the green 'M' sticker from rejection with the six-pointed star to re-qualification with the crown sticker. (The green 'M' and number stickers are not removed. They are only added on to show the history of the equipment.)

weights and measures mark weights and measures mark

The above are the old version of the stickers. The new stickers have the same prescribed crown and a similar six-pointed star, but the re-qualification stickers are overprinted with the identification number of the approved body.

weights and measures mark  weights and measures mark  weights and measures crown mark  weights and measures crown mark

Alternatively, a notice may be given by an inspector requiring repair within a specified period. It is, therefore, prudent to keep more complex equipment maintained by a competent service organization.

Automatic weighing equipment

Scales that are fully automated to fill a package without the intervention of an operator may not need to be normally passed as fit for use for trade - contact your local trading standards service for advice. All equipment used is required to be suitable for the process and sufficiently accurate. You are required to carry out your own checks to make sure that the equipment is properly maintained and accurate in addition to carrying out checks on the finished product for weight control (please see 'Packaged goods - average quantity').


Weights that are in use for trade in conjunction with weighing equipment must be stamped with the crown stamp. This is found in a lead plug at the base of the weight. It is a criminal offence to use any weight for trade if it shows the six-pointed star, as this is the sign that it has been rejected by an inspector.

Maintenance and use of weighing equipment

Scales can give incorrect readings because of poor practice or misuse. You should note the following regarding common problems with scales:

  • it is most important to use scales on a stable, vibration free, level surface - most will incorporate a level-indicator device, so make sure it reads level before trying to adjust for a zero balance display
  • scales must be correctly balanced before use, with any indicators reading zero (on electronic scales, the digital indications should not be blank prior to weighing) - if the scale does not start at zero, incorrect readings may be given
  • strong draughts, caused by a breeze or air conditioning systems, can affect some scales - make sure you consider these problems when siting the scale
  • keep the scale pan clean and free from debris underneath the pan itself - build up of debris or other matter under or adjacent to the scale pan can interfere with the weighing operation
  • regular checks of the scale with stamped weights will ensure that you do not inadvertently use a faulty or unjust scale for trade purposes
  • where possible, keep a record of the checks carried out, identifying what was done, when it was done, and who carried it out

Key legislation

Please note

This information is intended for guidance; only the courts can give an authoritative interpretation of the law.

The guide's 'Key legislation' links may only show the original version of the legislation. Information on amendments to UK legislation can be found on each link's 'More Resources' tab; amendments to EU legislation are usually incorporated into the text. Amending legislation is linked to separately where it is directly related to the content of a guide.

Last reviewed/updated: June 2013




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This page was last edited on 12/03/15