EXPLANATORY STATEMENT
Issued by the authority of the Chief Metrologist
National Measurement Act 1960
National Measurement Guidelines 2026
Purpose and Operation
The principal objects of the National Measurement Act 1960 (the Act) are to:
- establish a national system of units and standards of measurement of physical quantities;
- provide for the uniform use of those uniform units and standards of measurement throughout Australia;
- co-ordinate the operation of the national system of measurement; and
- provide the legal framework for a national system of trade measurement.
The Act and the National Measurement Regulations 1999 (the Regulations) prescribe SI (International System of Units) base units of measurement and Australian legal units of measurement. They also prescribe certain additional, non-SI, legal units of measurement that may be used for particular purposes.
The purpose of the National Measurement Guidelines 2026 (the Guidelines) is to support the national measurement system by prescribing a uniform system to express Australian legal units of measurement to ensure a common and consistent understanding of measurement units used in Australia and to align the expression of measurement units in Australia with internationally accepted practice.
Further details of the Guidelines are outlined in Attachment A.
Authority
Section 7B of the Act provides that the Chief Metrologist may make guidelines governing the way in which Australian legal units of measurement may be combined to produce Australian legal units of measurement, and the way in which Australian legal units of measurement may be combined with a prefix for the purposes of subsection 7A(3) of the Act.
Consultation
The National Measurement Institute undertook a public consultation from 24 November to 25 December 2025 to inform the remaking of the 2026 Guidelines. The consultation was targeted towards stakeholders who currently reference the existing National Measurement Guidelines 2016, including government agencies, measurement laboratories, and industry bodies. Three submissions were received, each of which supported the proposed changes to the Guidelines.
Statement of Compatibility with Human Rights
A Statement of Compatibility with Human Rights is set out at Attachment B.
Attachment A
Details of the National Measurement Guidelines 2026
Section 1 – Name
This specifies the name of the Guidelines as the National Measurement Guidelines 2026.
Section 2 – Commencement
This provides that the Guidelines commence the day after registration.
Section 3 – Authority
This section provides that the authority for the making of the Guidelines is section 7B of the National Measurement Act 1960.
Section 4 – Schedules
This section is a machinery provision that gives effect to the provisions in the Schedules to the Guidelines.
Section 5 – Definitions
This section sets out the definitions for terms referred to in the Guidelines as follows:
Act means the National Measurement Act 1960.
Product Symbol means a symbol used to indicate the product of 2 or more Australian legal units of measurement.
Regulations mean the National Measurement Regulations 1999.
SI Prefix means a prefix mentioned in Schedule 3 of the Regulations.
Section 6 – Objects
This section sets out the objects of the Guidelines, which is to establish a system to express Australian legal units of measurement by governing the way in which Australian legal units of measurement may be combined to produce an Australian legal unit of measurement, and how they may be combined with prefixes to produce Australian legal units of measurement.
Section 7 – Physical quantities
Section 7 makes clear that Australian legal units of measurement may be formed only for the physical quantities prescribed under the National Measurement Regulations 1999 (the Regulations). These are set out in Schedules 1 and 2 of the Regulations.
Section 8 – Combining Australian legal units of measurement
This section provides that if a physical quantity is formed by combining two or more physical quantities then the Australian legal unit of measurement used to describe the combined physical quantity would reflect the mathematical relations linking the corresponding physical quantities.
The section also provides that the resulting Australian legal unit of measurement may be then represented by either a name or symbol that is itself derived from an Australian legal unit of measurement. For example the Australian legal unit of measurement of pascal can either be represented as Pa or N/m2. See Schedules 1 and 2 to the Regulations for the list of names and symbols of Australian legal units of measurement.
Section 9 – Combining Australian legal units of measurement and SI prefix
This section provides that a decimal multiple or submultiple of an Australian legal unit of measurement other than a kilogram must be formed using a single SI prefix. This is because kilogram already contains a prefix (kilo) as part of its name.
The note to subsection (1) is an example how a decimal multiple or submultiple of an Australian legal unit of measurement is to be expressed.
The note to subsection (2) makes clear that kilogram is a SI base unit of measurement as prescribed by Schedule 1 to the Regulations.
Subsection (3) of section 9 provides that an additional derived unit of measurement, as listed under part 4 of Schedule 1 to the Regulations, may also be combined with another Australian legal unit of measurement to form an Australian legal unit of measurement. For example the amount of gram per mole unit may be represented as grams/mol.
In addition, this section provides that an Australian legal unit of measurement and a SI prefix may be combined with other Australian legal units of measurement symbols, as listed under Schedules 1 and 2 to the Regulations, to form a symbol for a compound unit that is an Australian legal unit of measurement. For example the Australian legal unit measurement of metre (m) with the prefix of kilo (k) can be combined with the non-SI unit of time (hour), represented with the symbol (h), to form km/h for a measurement of speed.
Section 10 – Australian legal units of measurement that must not be combined with prefixes
Section 10 sets out a list of Australian legal units of measurement which must not be combined with SI prefixes so as to avoid confusion. Further, any decimal multiple or submultiple of kilogram must be formed by attaching a prefix to gram as kilogram already contains a prefix.
The note under subsection (2) makes clear that for historical reasons, kilogram already contains a prefix.
Section 11 – Australian legal units of measurement that may only be combined with prefixes that form multiples of the unit
This section clarifies that the Australian legal units of measurement of tonne may only be combined with an SI prefix that gives a decimal multiple of tonne. The note to this section provides an example that kilotonne is acceptable but not millitonne. This is because millitonne is a decimal sub-multiple of a tonne.
Section 12 –Expression of Australian legal units of measurement
This section sets out requirements for expressing Australian legal units of measurement. The purpose of this is to align the expression of measurement units in Australia with internationally accepted practice.
Subsection (1) makes clear that the names and symbols of Australian legal units of measurement must not be used together in the same expression. The note underneath gives the example that km/h is acceptable but not kilometre/h.
Subsection (2) makes clear that an adjective or sign must not be added to the name or symbol of an Australian legal unit of measurement. The note underneath gives the example that Wa cannot be used as a unit for acoustic power.
Subsection (3) makes clear that the symbol for an SI Prefix must be placed immediately before the symbol for the Australian legal unit of measurement without an intermediate space. The note underneath gives examples of how this should operate including km for kilometre and MJ for megajoule.
Subsection (4) makes clear that for a decimal or multiple or submultiple of an Australian unit of measurement that is expressed as a fraction, an SI Prefix may precede the Australian legal unit of measurement in the numerator, or the denominator, or both if there is no other way to form an unambiguous expression, and should precede the Australian legal unit of measurement in the numerator. The note to this subsection provides examples of how this works in practice.
Subsection (5) provides that only a single SI Prefix may be used to form a multiple of a derived Australian legal unit of measurement.
Subsection (6) lists the symbols that may be used as a product symbol. These are a dot (·), a full stop (.) if the resulting expression is unambiguous, or a space where the Australian legal unit of measurement is not the same as the SI prefix. The note to the subsection provides an example of how the product symbols should be used.
Subsection (7) provides that the product symbol can only be used with symbols representing Australian legal units of measurement. The example below this subsection states that N·m is acceptable, but Newton·metre is not.
Subsection (8) provides that an Australian legal unit of measurement derived from the division of 2 other Australian legal units of measurement may be expressed using an oblique stroke (/), horizontal line (-) or negative exponent (-x). The note to this subsection provides examples of each of these expressions.
Subsection (9) makes clear that the oblique stroke (/) must not be repeated on a line unless parentheses are also used to avoid ambiguity. For complex expressions, however, negative exponents or parentheses must be used.
Subsection (10) specifies that a space must be left after the numerical value of an Australian legal unit of measurement and before the name or symbol of the unit of measurement.
Subsection (11) creates an exception to subsection (10). Subsection 12(10) of these Guidelines do not apply when expressing the numerical values and the symbols for degrees, minutes and seconds of either (a) geographic coordinates, or (b) plane angles.
Attachment B
Statement of Compatibility with Human Rights
Prepared in accordance with Part 3 of the Human Rights (Parliamentary Scrutiny) Act 2011
National Measurement Guidelines 2026
This Legislative Instrument is compatible with the human rights and freedoms recognised or declared in the international instruments listed in section 3 of the Human Rights (Parliamentary Scrutiny) Act 2011.
Overview of the Legislative Instrument
The National Measurement Guidelines 2026 support the national measurement system by prescribing a uniform system to express Australian legal units of measurement to ensure a common and consistent understanding of measurement units used in Australia and to align the expression of measurement units in Australia with internationally accepted practice.
Human rights implications
This Legislative Instrument does not engage any of the applicable rights or freedoms.
Conclusion
This Legislative Instrument is compatible with human rights as it does not raise any human rights issues.
Dr Victoria Anne Coleman
Chief Metrologist