Trade Approved Scales and Balances

What is a Trade Approved Scale or Balance?

A trade approved scale or balance is essential for ensuring accurate transactions when selling goods by weight. This guarantees that both vendor and customer receive a fair deal. In the UK, one of the more commonly applicable sections for Trade approval is ‘the determination of mass for commercial transactions.’ As defined in ‘3. Scope’ by NAWI as a legal requirement. Therefore, businesses must have a trade approved scale if they sell by weight or any of the scenarios defined.

How do trade approved scales work?

Trade approved scales are meticulously calibrated and locked to specific increments to prevent rounding errors, thus ensuring precise measurements. For instance, when weighing 5g of gold, the scale will only display 5g once it reaches exactly 5g, not 4.9g.

Unlike other scales, trade approved scales also get a seal placed over the calibration switch, or components which can affect the weighing, by the manufacturer to prevent tampering. The scale remains legal for trade use unless the seal is broken. If the seal is compromised, the scale must be recalibrated by trading standards, or an approved body and a new seal applied.

(We can re-seal/stamp some items!)

How do I know if my scale is trade approved?

Trade approved scales, also known as EC stamped, approved, legal for trade, verified, or stamped scales, are identifiable by a seal or stamp. Often, a green or black ‘M’ on the product or ‘M’/‘EC’ in the product code indicates trade approval.

Who needs trade approval?

It’s a common misconception that trade approval only applies to all items sold by weight, although true most of the time, this is not always the case.

The Non-Automatic Weighing Instruments Regulations 2016 (NAWI for short) state they “define a non-automatic weighing instrument as a weighing instrument that: (a) serves to determine the mass of a body by using the action of gravity on that body and which may also serve to determine other mass-related magnitudes, quantities, parameters and characteristics; and (b) requires the intervention of an operator during weighing.”

They provide 6 categories that outline which applications require trade approved scales/balances giving examples.

1. “the determination of mass for commercial transactions”
2. “the determination of mass for the calculation of a toll, tariff, tax, bonus, penalty, remuneration, indemnity or similar type of payment”
3. “the determination of mass for the application of laws or regulations or for an expert opinion given in court proceedings”
4. “the determination of mass in the practice of medicine for weighing patients for the purposes of monitoring, diagnosis and medical treatment”
5. “the determination of mass for making up medicines on prescription in a pharmacy and determination of mass in analyses carried out in medical and pharmaceutical laboratories”
6. “the determination of price on the basis of mass for the purposes of direct sales to the public and the making up of pre-packages”

In short, this ranges from commercial transactions, paying a toll/penalty, mass-based calculation for penalty/tolls to medicine, medical and retail.

These applications span various industries including:

• Food stuffs
• Soaps
• Meat and fish
• Alcohol
• Fuels
• Precious metals
• Jewels
• Animal feeds
• Packed products
• Delis
• Frozen yogurt shops
• Farms
• Landscaping material
• Medication and chemical compounds
• Postal requirements
• Laundry tariffs
• Sweets

What are the different classes of trade approved scale/balance?

So, if you fall into one of the above categories what class of trade approved scale should you purchase…

Put simply depending on what application you have you may require a higher scale division and accuracy.

An easy way to work out what class you need is to take your capacity and divide it by the readability this will give you your ‘divisions’ or ‘scale interval’. You can then use the below table to figure it out!

For example: The Ohaus Ranger 7000 R71MD35 Industrial Balance – Trade approved has 35kg Capacity (35,000g) and 5g Readability; 35,000/5=7,000*.

Class IIII has a maximum of 1000 divisions/intervals that means you have entered the next bracket of accuracy class, up to 10,000 divisions.

As you can see 10,000 can be Class III or Class II. However, it is not class II as the readability of the scale required is 5g*. So, if your requirement was for a trade approved scale with 35kg capacity and 5g readability you would need a Class III trade approved scale.

The Ohaus Ranger 7000 R71MD35 Trade Approved may be perfect for your needs. Often the manufacturer would have done the work for you as they must comply to these rules.

https://www.nist.gov/system/files/documents/2025/01/06/2-20-25-HB44-20240103.pdf (Page 20)

Why are there non-Trade Approved scales/balances?

If trade-approved scales are necessary in many situations, why aren’t all scales trade-approved?

Manufacturers of trade-approved scales have to invest more effort and technology to ensure the scales are accurate, legal and fair, which increases costs. Typically, trade-approved scales are only required at the end of a production line when selling to a customer. Other scales in the production line do not need to be trade-approved. For example, in a food production line, non-trade scales might be used to ensure no product is wasted and is measured correctly. When the vendor is ready to sell to a supermarket, the final scale in the production line will be trade-approved.

Use this guide or contact us for expert advice or reach out to Trading Standards directly.

Now that you have all the information, you can see all full range of Trade Approved scales here.