Approved Weighing Machines

Scales approved by Trading Standards for buying and selling precious metals 



Approved for use in trade means buying or selling on a value-for-weight basis. This applies to any transaction, whether in a shop, pawnbrokers, antiques fair, market or even a boot sale, even if you do not regard yourself as a trader. So if you are offering to buy or sell anything by weight, you MUST use an approved balance, it is the law; if you are not buying or selling by weight, then there is no need to read on.

In this article I refer to Weights & Measures Inspectors - these are Trading Standards Officers who happen to deal with weights and measures.


When we joined the EU and agreed to abide by EU standards the cost of approved scales fell by half, quite literally overnight. Now that we have left the EU we will be reverting to UK standards and (surprise-surprise!) prices have shot up.  

All the models we stock are approved, even if they date from before the new laws, and they will remain approved forever.  


If you buy or sell by weight (i.e. an amount of money per gram or per ounce) then you are using the balance 'in trade' and it must be approved. However, if you use it as part of your valuation but do not base the value on weight (e.g. jewellery where the main value is in gemstones, diamonds or antique value) then you do not need an approved balance - you are still a trader, but you are not using it 'in trade'.

Any Weights & Measures Inspector will notice if you are buying or selling by weight, even if you pretend otherwise. He can see whether you are calculating a price based on weight or if you are calculating the price by carefully evaluating gemstones and hallmarks.

In the past I said that auctions were an 'iffy' area. Following a 2½ hour meeting with a Weights and Measures Inspector, I can now clarify the position: an auction house must use an approved balance if the item description includes the weight. 

At fairs and markets the same laws apply. Traders buying scrap must use an approved balance. You may say to yourself, "But nobody uses an approved balance in my market, and there has never been a problem." Maybe everyone unloading at the market parks on a double yellow line and there has never been a problem. I can only tell you about the law, not how it is enforced.


The actual standards for Weights and Measures are determined by the National Measurement Office who study the law, look at the science, and issue guidelines to Weights & Measures Authorities. The law is enforced by Weights and Measures Inspectors, they work for the Trading Standards department at your Local Council. You can find them by going to Trading Standard's Home Page (enter your postcode in the box at the top and click 'go'). If you wish to study the law yourself, see the Weights & Measures Act 1985 and its many amendments. Then, if you disagree with an inspector, you may accept his offer to have the matter settled in court. Of course, Brexit has caused many complications, see the latest information.

Each Local Council's Trading Standards Department enforces the law at a local level. So whilst the law is consistent, each Local Council has its own priorities regarding enforcement (i.e. they might have more important things to do)


First, the easy bit. A weighing machine used in trade must be stamped with a special sticker. These stickers are seals that are carefully placed over vital screws on the balance, if you break the seal it will no longer be approved.

There are four Classes (grades) of approved balance:

  • CLASS 4 need not concern you, it is for heavy items such as heavy goods vehicles
  • CLASS 3 need not concern you, it is for general goods, e.g. food (anything from packets of herbs to bags of fruit)
  • CLASS 2 is for items that have a high value per gram, specifically precious metals (including silver)
  • CLASS 1 need not concern you, it is for scientific applications, e.g. for weighing down to 0.0001g


- Complication No. 1: 1g or 0.1g or 0.01g?

When you buy an approved CLASS 2 balance the manufacturers might give you its specification as, for instance, 6000g in steps of 0.1g. What they don't tell you is that once it's approved, you are not supposed to use that last decimal place when used "in trade". So, for instance, having spent hundreds of pounds and thinking you will be weighing down to 0.1g you will discover that the balance now has a red cross painted over that last decimal place so that it only reads to the nearest 1g. (though the 0.1g will still be visible under the red cross). For your own purposes (away from customers, for your own valuation purposes) you may weigh to 0.1g, but when buying by weight you are supposed to ignore the 0.1g and work to the nearest 1g.

All the balances we sell have this two-tier system, a more sensitive reading for your own use and a less sensitive reading for buying precious metals by weight.

- Complication No. 2: buying or selling?

If you are selling by weight, the customer must be able to see the display and you must never use a balance with a "crossed out" digit, but you can use it to price items by weight (ignoring that "crossed out digit") out of sight of the customer.

Our balances do not have a display facing the customer and they all have a "crossed-out" digit, therefore they cannot be used for selling, they can only be used for buying.  

Why so complicated?? - because when the law was made, it was assumed that retailers sold goods by weight (mostly groceries) but it never occurred to the law-makers that a trader might buy by weight, and so the words "and buying" were not included in regulations.

- Complication No. 3: balances calibrated by area

Some CLASS 2 balances are calibrated for a particular area (usually a town, sometimes a full postcode). This is to allow for variations in gravity. So if, for instance, you use a balance in central Liverpool, then it will be calibrated for central Liverpool, you can't legally use it anywhere else.

We have found a simple solution to this. We no longer sell this type of approved balance. Our approved balances can be used anywhere.



Check your balance whenever it is moved. If you work at fairs and markets, that includes moving to a new venue, it also includes moving the balance from one side of the stall to the other. Even if the balance lives on a shop counter and is never moved (not even by a few inches) it is wise to check it every few weeks.

To check it, buy a weight, any weight that is near (or at) the top of the balance's range. Switch the balance on, place the weight on the platform, check the reading. It really is no more complicated than that.