Chapter II - Standard Weights and Measures
Section 5
Section 5: Base unit of weights and measures
Section 5 names seven base units: metre, kilogram, second, ampere, kelvin, candela and mole. Specifications of these and derived or other units are prescribed by rules.
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Need advice on Section 5?
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
(1) The base unit of— (i) length shall be the metre; (ii) mass shall be the kilogram; (iii) time shall be the second; (iv) electric current shall be the ampere; (v) thermodynamic temperature shall be the kelvin; (vi) luminous intensity shall be the candela; and (vii) amount of substance shall be the mole.
(2) The specifications of the base units mentioned in sub-section (1), derived units and other units shall be such as may be prescribed.
Introduction
The seven SI base quantities are length, mass, time, electric current, thermodynamic temperature, luminous intensity and amount of substance. Section 5 names their corresponding units, while rules supply specifications.
Section 7 makes the section 5 base units standard units and addresses technical particulars.
Key takeaways
Scope and trigger
The seven SI base quantities are length, mass, time, electric current, thermodynamic temperature, luminous intensity and amount of substance. Section 5 names their corresponding units, while rules supply specifications.
Operational step
Classify the physical quantity before choosing a unit or calibrating an instrument. For a derived quantity such as area or volume, trace it to prescribed derived or other unit specifications.
Limit
The listed base units do not exhaust all lawful derived units. A familiar unit name does not replace the statutory distinction between a base unit and a prescribed derived unit.
Who and what it covers
The seven SI base quantities are length, mass, time, electric current, thermodynamic temperature, luminous intensity and amount of substance. Section 5 names their corresponding units, while rules supply specifications.
Section 7 makes the section 5 base units standard units and addresses technical particulars.
How to apply it
Classify the physical quantity before choosing a unit or calibrating an instrument. For a derived quantity such as area or volume, trace it to prescribed derived or other unit specifications.
Map each measured property to the statutory base unit and the relevant technical rule; avoid treating an informal trade unit as a statutory base unit.
Boundary and exceptions
The listed base units do not exhaust all lawful derived units. A familiar unit name does not replace the statutory distinction between a base unit and a prescribed derived unit.
Hypothetical example
Hypothetical: a laboratory documenting thermodynamic temperature identifies kelvin as the base unit and checks applicable technical specifications before instrument validation.
Practical preparation
Map each measured property to the statutory base unit and the relevant technical rule; avoid treating an informal trade unit as a statutory base unit.
Primary sources
The statutory text is drawn from the official Act copy.
Practical checklist
Do
- Identify the physical quantity being measured.
- Use the appropriate one of the seven named base units.
- Check prescribed specifications for derived or other units before instrument approval.
Avoid
- Do not treat section 5 as dispensing with its stated conditions, exceptions or prescribed details.
Glossary
- Derived unit
- A unit formed from base units, with specifications addressed by the Act and rules.
- Prescribed
- Set by rules made under the Legal Metrology Act, 2009.
Frequently asked questions
Is Celsius listed as the base unit of thermodynamic temperature?
No. Section 5 lists kelvin; other permitted units depend on the applicable rules.
What are the seven base units?
Metre, kilogram, second, ampere, kelvin, candela and mole.
Need help applying this provision to your situation?
Contact BizeneedLast updated 10 October 2026