Main laws

New Zealand Act

Weights and Measures Act 1987

The Weights and Measures Act 1987 sets the rules for using weights and measures in trade in New Zealand.

In forceNew ZealandPlain-English guide8 practical checks

Plain-English explainers, not legal advice. Use the linked official source for section-level detail, and get advice for your situation.

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Quick read

  • The Weights and Measures Act 1987 matters whenever quantity affects a sale in New Zealand.
  • If your business sells goods by kilogram, litre, metre, area or number, or states quantity on packaging, labels, invoices, delivery notes or advertising, this Act is likely...

Likely relevant if

  • Retailers that sell goods by weight, volume, length, area or number, including supermarkets, butchers, greengrocers, bakeries and bulk food stores
  • Manufacturers, packers and brand owners supplying packaged goods with a stated quantity on the package or label
  • Importers, wholesalers and distributors supplying packaged goods or quantity-based goods into New Zealand

Check first

  • Use metric weights and measures for trade in New Zealand unless the Act expressly provides otherwise.
  • Use the metric system in advertising goods for sale, subject to the Act’s exceptions.
  • Where the Act applies, sell goods by net weight or net measure as required.

What this Act is for

The Weights and Measures Act 1987 sets the framework for how quantity is measured and stated in trade in New Zealand. Its purpose is to contribute to a trading environment where consumers are protected, businesses compete effectively, and both consumers and businesses can participate confidently.

In practical terms, the Act does two main things. It establishes a system of weights and measures to be used for trade, and it regulates the use of weights and measures for trade. That reaches beyond a shop scale. It can affect packaging, labels, advertising, invoices, delivery notes and trade equipment.

If quantity is part of the bargain, this Act is worth checking. It is especially relevant where the quantity supplied affects price, customer expectations or the description of the goods being sold.

Practical sense check

  • You sell goods by weight, volume, length, area or number
  • You state quantity on packaging or labels
  • You advertise goods with a quantity statement
  • You use scales, pumps, dispensers or other measuring instruments in customer transactions
  • You issue invoices or delivery notes that state quantity

Who is in scope and who is usually out

The Act applies to the use of a weight, measure, or weighing or measuring instrument in connection with a transaction involving money or money’s worth where the transaction is by reference to quantity, or includes a statement of quantity, and the weight, measure or instrument is used to determine or state that quantity.

That means the Act can apply in retail, wholesale and supply settings. It is not limited to over-the-counter sales. If quantity is part of the transaction, the Act may be relevant even where the quantity appears on a package, a label, an invoice, a delivery note or an advertisement.

Key points

  • Usually in scope - goods sold by kilogram, gram, litre, millilitre, metre, square metre or number
  • Usually in scope - prepacked goods with a stated quantity
  • Usually in scope - retail weighing and measuring at the point of sale
  • Usually in scope - quantity statements used in supply documents
  • Usually out of scope - quantity determinations for despatch to a destination outside New Zealand
  • Usually out of scope - water supplied through pipes
  • Usually out of scope - electricity
  • Usually out of scope - gas supplied through pipes, except liquefied petroleum gas in liquid form

The Act also contains a presumption about possession. If a weight, measure, or weighing or measuring instrument is found in the possession of a person carrying on trade, or on trade premises or trade vehicles, that person is deemed to possess it for use for trade unless the contrary is proved.

So equipment sitting in the business can still matter, even if staff say it is not currently being used. Old scales, spare weights or measuring devices kept on site should not be ignored.

The main trigger points for businesses

Most businesses do not need to read every section to spot the risk areas. The Act is most likely to matter when quantity affects price, supply or customer expectations. If your business relies on quantity statements to sell goods, or uses equipment to determine quantity, you should assume the Act is relevant and then check the detail.

Common trigger points include selling produce by weight, filling containers by volume, selling fabric by length, supplying goods by number, or advertising a product as containing a stated amount. Another trigger point is using equipment that determines what the customer gets or pays for.

Practical sense check

  • You price goods per kg, g, L, ml, m or by number
  • You weigh or measure goods at checkout or before dispatch
  • You fill bottles, tubs, bags or containers for sale
  • You print quantity on a package or label
  • You advertise quantity on a website, shelf label, catalogue or promotion
  • You use a public weighing instrument or customer-facing measuring device
  • You keep scales or measuring instruments on trade premises

Metric units are the starting rule

The Act says that, except as expressly provided in the Act, weights and measures of the metric system are the only weights and measures used for trade in New Zealand. For the purposes of the Act, the kilogram and the metre are the source from which all weights and measures are derived.

The Act also includes an obligation to use the metric system in advertising goods for sale, with exceptions dealt with in the Act. For many businesses, this means quantity statements in product listings, labels, shelf tickets and promotional material should be checked for lawful unit use.

Key points

  • Length examples in Schedule 1 include metre, kilometre, centimetre and millimetre
  • Area examples include square metre and hectare
  • Volume examples include litre and millilitre
  • Weight examples include kilogram, tonne, gram, milligram and metric carat

If your systems, labels or templates were copied from overseas suppliers, this is an area to review carefully. The Act does contain exceptions, but you should not assume a non-metric trade statement is safe without checking whether an exception actually applies.

Selling goods by quantity

Part 3 of the Act deals with the sale of goods by weight, measure or number. The Act includes an obligation to sell goods by net weight or measure, an obligation in respect of invoice or delivery note, rules about counting of goods sold by retail, rules about weighing and measuring of goods sold by retail, and offences for short supply and incorrect stated quantity.

For a business owner, the key point is that if quantity is part of the sale, the quantity supplied must match what is charged for, sold, or stated. The Act is aimed at both the physical supply of goods and the quantity information that supports the transaction.

Practical sense check

  • Check whether goods sold by weight or measure are sold on a net basis where the Act requires it
  • Check whether quantity shown on invoices or delivery notes aligns with the goods actually supplied
  • Check retail processes for counting, weighing and measuring goods sold to customers
  • Check that staff do not round, estimate or substitute quantity in a way that creates short supply risk
  • Check that quantity stated to the customer matches the quantity used to set price

This part of the Act is especially relevant for deli counters, produce sales, meat sales, bulk goods, liquids sold by measure, and wholesale supply where quantity is recorded as part of the deal. It can also matter where goods are sold by number and the count is part of what the customer is paying for.

Packaged goods and stated quantity

If you sell packaged goods with a quantity statement, this is one of the clearest compliance areas under the Act. The Act creates an offence to supply weight, measure or number not in accordance with stated quantity. It also defines non-standard packages and inadequate packages by reference to error amounts set in regulations made under section 41A.

The Act itself does not set all of the tolerances in the text above. Instead, it allows regulations to prescribe the maximum amount of error allowed in a single selected package, in a group of selected packages, and formulas and sampling rules for groups and lots of packages.

That means packaged-goods compliance is not just a label issue. It is also a process issue. If your business packs food or other goods, you should check whether your filling, weighing, measuring and quality control processes are capable of keeping actual contents aligned with the stated quantity across a batch or lot.

The Act also recognises catch weight goods, which are goods enclosed in a package that cannot be portioned to a predetermined quantity because of their nature and are usually sold in varying quantities. If you deal with variable-weight packaged goods, quantity controls still matter.

Key points

  • A package can be non-standard if it contains less than the stated quantity by more than the error amount set by regulations
  • A package can be inadequate if the deficiency is more than twice the error amount set by regulations
  • Regulations may also deal with package sampling, group testing and lot-based assessment
  • A lot of packages means packages of the same kind, with the same stated quantity, available for inspection at the same time and place

Scales, pumps and other measuring instruments

Part 4 of the Act deals with stamping, verification and approval of weights and measures. The Act includes marking contents, approval of appliances, verification marks, certificates of accuracy, and a requirement for certificates of accuracy for certain weighing or measuring instruments.

This is important if your business uses equipment to determine quantity for trade. The Act supports a system where some equipment must be approved, verified, stamped or covered by a certificate of accuracy. But the detailed classes, processes and conditions can depend on regulations.

Practical sense check

  • Identify every weighing or measuring instrument used to determine quantity in trade
  • Check whether the instrument type needs approval or verification
  • Check whether the instrument should carry a mark of verification
  • Check whether the instrument is one of the certain instruments that requires a certificate of accuracy
  • Check whether the instrument remains accurate in day-to-day use and has not drifted out of tolerance

The Act also creates an offence to use or possess a false or unjust weight or measure. So the risk is not limited to deliberate fraud. Equipment that is inaccurate, unsuitable or not lawfully in trade use can create exposure even before a customer complaint arises.

The regulations can also deal with tolerated error, approval conditions, limits on lawful use, prohibited kinds of instruments, public weighing instruments, liquid measuring instruments and the form and content of tickets showing volume passed through those instruments.

Documents, advertising and quantity statements

The Act reaches more than the physical act of weighing or measuring. It includes an obligation in respect of invoice or delivery note, and an obligation to use the metric system in advertising goods for sale. So your paperwork and marketing can create compliance issues even where the goods themselves are correctly measured.

The safest approach is consistency. The quantity on the package, the quantity in the advertisement, the quantity on the invoice or delivery note, and the quantity actually supplied should all line up. Mismatches are the kind of problem this Act is designed to address.

Documents to keep in order

  • Review website listings and catalogues for quantity statements
  • Check shelf labels and promotional material for metric unit use
  • Review invoice and delivery note templates used for quantity-based sales
  • Check that quantity descriptions in your systems match the goods actually supplied
  • Check imported label copy and inherited templates before using them in New Zealand trade

The Act also gives regulation-making power over some document-related detail. For example, regulations may deal with the form and content of tickets showing the volume of substances that have passed through liquid measuring instruments, and with recording the weight of goods at the time they are weighed.

Inspectors, enforcement and penalties

The Act gives Inspectors powers and sets out offence and infringement pathways. Proceedings for an offence against the Act must be commenced by an Inspector. The Act also provides for infringement notices and says that if an infringement notice is issued, a criminal record must not be created in respect of the infringement offence.

Not every breach is dealt with in the same way. The Act defines infringement offences to include offences against sections 8, 10, 14, 15, 15A, 16, 16A, 17, 18, 21, 22B and 24, as well as breaches of regulations prescribed as infringement offences.

Key points

  • A person who commits an infringement offence is liable to a fine not exceeding $10,000 on conviction
  • A person who commits an offence against section 32(a) is liable to imprisonment for up to 3 months or a fine not exceeding $10,000
  • Any other offence under the Act carries, for an individual, a fine not exceeding $10,000 and for a continuing offence a further fine not exceeding $100 per day or part day
  • Any other offence under the Act carries, for a body corporate, a fine not exceeding $30,000 and for a continuing offence a further fine not exceeding $250 per day or part day

The court may also order forfeiture of weights, measures, instruments or goods involved in the offence. For offences under sections 16, 16A or 17, the court may order the offender to make good the deficiency in goods or money.

For a business, that can mean more than a fine. It can mean replacement supply, refunds, stock checks, equipment review and operational disruption.

Practical checks before you rely on this page

This Act gives the main framework, but some important detail sits in regulations. Before relying on a high-level summary, check the exact trade activity involved and whether regulations add more specific rules for your product, package type, instrument type or document format.

This matters most for packaged goods tolerances, sampling methods, verification and stamping detail, and which instruments require certificates of accuracy. If your business trades heavily on quantity, a targeted compliance review is usually more useful than a general read of the Act.

Sense check

  • Confirm whether your goods are sold by weight, measure or number for the purposes of the Act
  • Confirm whether any exception applies before using non-metric trade statements
  • Confirm whether your packaged goods are subject to regulation-based error tolerances or sampling rules
  • Confirm whether your instruments need approval, verification, stamping or a certificate of accuracy
  • Confirm whether your invoice, delivery note and advertising templates match the quantity actually supplied

Dates and status

This is a principal Act that is in force in New Zealand. The current consolidated version currently in force is the latest version as at 30 March 2025.

The Act received assent on 16 March 1987. Subject to sections 17(2) and 18(4), it came into force on 1 April 1987.

Because the Act has been amended over time, businesses should make sure they are working from the current version and any relevant regulations before updating labels, advertising, packaging processes or trade equipment procedures.

Common questions

Does this Act only apply to shops using scales?

No. It applies more broadly wherever weights or measures are used for trade. That can include retail sales, wholesale supply, packaged goods, advertising, invoices, delivery notes and the use of weighing or measuring instruments to determine quantity in a transaction.

Do I have to use metric units in trade?

As a starting point, yes. The Act says weights and measures of the metric system are the only ones to be used for trade in New Zealand, except where the Act expressly provides otherwise. The Act also includes obligations to use the metric system in advertising goods for sale, subject to exceptions in the Act.

What if I sell packaged goods with a quantity on the label?

You need to be careful that the goods supplied match the stated quantity. The Act creates an offence for supplying weight, measure or number not in accordance with stated quantity. It also recognises non-standard packages and inadequate packages by reference to error amounts set under regulations.

Does the Act require every business to keep general records?

The Act includes obligations relating to invoices or delivery notes, and it reaches documents used in quantity-based trade. But it is safer to treat internal records as a practical compliance step rather than assume the Act creates a broad standalone record-keeping duty for all businesses.

Do all scales and measuring devices need a certificate of accuracy?

Not necessarily. The Act refers to certificates of accuracy and says certain weighing or measuring instruments require one. Which instruments are covered, and some of the detail around certificates, depends on the Act and regulations.

Are water, electricity and gas covered?

Not generally. The Act does not apply to the measurement or sale of water supplied through pipes, electricity, or gas supplied through pipes, other than liquefied petroleum gas in liquid form.

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