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How to check if a seller has sold you the correct amount, and what to do if it's a short measure.

Your rights

The Weights and Measures Act sets out rules for selling goods by quantity in New Zealand. It’s there to make sure businesses sell correct quantities, and you get what you pay for. Goods sold by weight, volume, length or number must be:

  • accurately weighed, measured or counted
  • clearly labeled with the correct net quantity.

Goods bought by weight or measure must be sold to you by net weight or measure. This means the weight of any packaging must be excluded from the weight or measure statement.

Examples of goods sold by weight or measure include:

  • coffee beans sold by kilo
  • firewood sold by cubic metre
  • potting mix sold by litre
  • railway sleepers sold by number.

Trade measurements - for consumers(external link) — Trading Standards

Measuring rules for different types of products

Click on a heading to find out more about buying by weight, measure or number.

Goods weighed, measured or counted at the time of sale must be done so in front of you and you must be able to see the whole operation. Most modern weighing instruments have a tare button. This should be used to zero — or deduct — the weight of the packaging or container before weighing the goods. Always check the scale or petrol pump is on zero before you are served.

Where goods are pre-packed on the premises, you can request they be re-weighed, measured or counted in front of you. All goods must be sold in metric units, eg grams, kilograms, millilitres, litres or metres.

Generally, pre-packaged goods which are marked with their quantity must contain the amount stated on the package.

Pre-packaged goods of the same kind and stated quantity — eg 500g packs of butter — must meet the 'average quantity system' rules. These rules set out strict specifications that packers must abide by to control the quantity of pre-packed goods. Although it is possible to have a few pre-packed goods that contain slightly less than the stated amount, on average the stated quantity must be correct.

Other pre-packed goods of variable quantity, eg joints of meat, must contain at least the stated quantity. The statement could be on a label, invoice, a scale display or whatever the trader tells a customer it is.

You can look for a 'certificate of accuracy' sticker which shows scales are checked annually. You should also find (often on the side or back of the scales) a small round lead plug or an adhesive destructible label with a crown or the letters AP and a number. Sometimes it may be a lead seal and wire. These show the scales are approved for trade and were tested before being put into use.

The same rules apply if you buy from a roadside stall. If the goods are weighed in front of you it is worth checking that the scales the trader is using are suitable.

Firewood is sold as a thrown measure, rather than a stacked one. It can be sold by either:

  • volume, eg three cubic metres
  • description, eg a truckload, trailer load or sackful.

If you buy by volume, check if Trading Standards has approved the truck and/or measure — look for a sign stating the truck or measure's size, eg “3 cubic metre” or “3m3”. Trading Standards can advise if a trader in your area has a certificate of approval.

Also look for either:

  • a stamped lead plug with a crown on it
  • a Certificate of Approval carried in the vehicle at all times.

When you buy by volume, the seller should give you a written invoice showing the quantity delivered.

Coal (or coke or carbonettes) must be weighed before the sale, unless you are filling your own bags or trailer.

If coal is sold in closed bags, the weight must be shown on the bag or on an invoice or delivery note.

If coal is sold in open bags, the seller must provide a written notice showing either:

  • net weight of coal each bag and number of bags delivered
  • total weight of bags delivered.

If coal is sold loose, the driver of the delivery vehicle must give you a written notice showing the weight.

Garden and landscape supplies can be sold to you by either:

  • weight or measure
  • number
  • description, eg a scoop or truckload.

If things go wrong

If the quantity is not marked on a package, you can ask for a written statement of the goods.

If you think you have been sold a short amount, you can:

  • Ask the seller to re-weigh or measure the goods in front of you.
  • Tell the seller you believe they have sold you a short weight or measure.
  • Check to see whether their scale or the petrol pump has a current certificate of accuracy — you can rely on scales and pumps that have a current certificate.

Complain to Trading Standards

If you can't resolve it with the seller — or you think a seller's measuring equipment doesn't meet the rules — you can report it to Trading Standards.

Trading Standards can't act on your behalf about your specific issue. But reports from the public help it identify sellers, industries or equipment suspected of regularly breaking the rules. Trading Standards can:

  • seize short weight or measure goods
  • seize inaccurate weighing or measuring equipment
  • fine the seller if they have breached the Weights and Measures Act.

Trade measurement - Making a complaint(external link) — Trading Standards


Example — Amount seems less than ordered

Janet orders three cubic metres of pine firewood, but when it arrives she notices the amount seems to be less than she had delivered last year. She talks to the seller, who says it is more or less three cubic metres but that he has not checked. He agrees to check the amount delivered against the approved volume measure.

Example — Petrol pump bill seems too high

John fills up his car with 100 litres, but at the till he is charged for 102 litres. John thinks he might have been charged for more petrol than he received. The attendant explains petrol pumps are very precise, and fuel tanks can hold slightly more or less than they are meant to. John is satisfied he received all the petrol he paid for.