Chapter II - Standard Weights and Measures
Section 4
Section 4: Units of weights and measures to be based on metric system
Every unit of weight or measure under the Act must follow the metric system based on the international system of units.
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Need advice on Section 4?
This article is for general information. Refer to the Legal Metrology Act, 2009 official text for the official provisions. If you need professional advice for your situation, contact Bizeneed.
Statutory text
Bare law
Every unit of weight or measure shall be in accordance with the metric system based on the international system of units.
Introduction
Section 4 fixes the metric SI basis for a unit of weight or measure. It applies to the unit itself; separate sections regulate particular commercial communications and the standards of an instrument.
Read with base units in section 5, standard units in section 7 and transaction communications in section 11.
Key takeaways
Scope and trigger
Section 4 fixes the metric SI basis for a unit of weight or measure. It applies to the unit itself; separate sections regulate particular commercial communications and the standards of an instrument.
Operational step
Inventory all measurement units used in instruments, contracts and labels. Convert legacy non-metric fields to appropriate metric units and confirm the prescribed symbol and expression under the relevant rules.
Limit
A permitted explanatory conversion is different from making a non-metric unit the operative legal measure. Section 4 does not itself determine which commodity must be sold by weight, measure or number.
Who and what it covers
Section 4 fixes the metric SI basis for a unit of weight or measure. It applies to the unit itself; separate sections regulate particular commercial communications and the standards of an instrument.
Read with base units in section 5, standard units in section 7 and transaction communications in section 11.
How to apply it
Inventory all measurement units used in instruments, contracts and labels. Convert legacy non-metric fields to appropriate metric units and confirm the prescribed symbol and expression under the relevant rules.
Review instruments, price displays, invoices and technical specifications for prescribed metric units before commercial use. Check the detailed unit rules when choosing symbols or derived units.
Boundary and exceptions
A permitted explanatory conversion is different from making a non-metric unit the operative legal measure. Section 4 does not itself determine which commodity must be sold by weight, measure or number.
Hypothetical example
Hypothetical: a seller plans to invoice commodity weight only in pounds. It revises the transaction to use the applicable standard metric unit.
Practical preparation
Review instruments, price displays, invoices and technical specifications for prescribed metric units before commercial use. Check the detailed unit rules when choosing symbols or derived units.
Primary sources
The statutory text is drawn from the official Act copy.
Practical checklist
Do
- Identify every weight or measure used in the transaction.
- Compare its unit with the applicable metric SI unit.
- Update quote, display and invoice templates consistently.
Avoid
- Do not treat section 4 as dispensing with its stated conditions, exceptions or prescribed details.
Glossary
- SI
- The international system of units on which the Act bases metric weights and measures.
- Prescribed
- Set by rules made under the Legal Metrology Act, 2009.
Frequently asked questions
Does section 4 itself list every permitted symbol?
No. It states the metric-system basis; other provisions and rules supply details.
Can a non-metric unit be the sole domestic transaction unit?
Section 4 requires units of weight or measure under the Act to be metric and SI-based; check the applicable rules for specific permitted expressions.
Need help applying this provision to your situation?
Contact BizeneedLast updated 10 October 2026