Use metric units (grams, kilograms, millilitres or litres) when you sell packaged or loose goods. You can show an imperial measurement alongside, but it must not stand out more than the metric one. Draught beer and cider, milk in returnable containers and precious metals are the only goods you can sell in imperial measures.
The equipment you use to weigh or measure goods for sale must be suitable, and you cannot use domestic scales to weigh packaged goods. Ask your local Trading Standards service what equipment suits your business.
Weights and measures law (opens in a new tab)
Units of measurement, specified quantities and packaged goods.