Economic, Commercial and Intellectual Property Laws · Legal Metrology

Units and Standards of Weights and Measures under the Legal Metrology Act

Updated 11 October 2026 · Fact-checked

Under the Legal Metrology Act, 2009, every unit must follow the metric system based on the international system of units (section 4). Section 5 fixes seven base units. Reference, secondary and working standards must be verified and stamped (section 9). Before making or importing a weight or measure, you must seek model approval (section 22).

Understand Metrology Units and Standards of Weights and Measures

Legal metrology is the law on measurement used in trade. If a shopkeeper weighs rice or a petrol pump measures fuel, the buyer must be able to trust the figure. The Act builds that trust by fixing one system of units and one chain of standards.

Start with units. Section 4 says every unit of weight or measure must follow the metric system based on the international system of units. Section 5 then names the base units: metre for length, kilogram for mass, second for time, ampere for electric current, kelvin for thermodynamic temperature, candela for luminous intensity and mole for amount of substance. The specifications of base, derived and other units are to be as prescribed by rules.

Next, the standard units. Under section 7, the base units are the standard units of weights and measures, and the base unit of numeration (section 6) is the standard unit of numeration. The Central Government prepares objects or equipment to derive the value of units, as prescribed. Physical characteristics, tolerances, period of re-verification and test methods are also prescribed. Under section 8, a weight or measure is a standard one only if it conforms to the standard unit and to the applicable parts of section 7. No other weight, measure or numeral may be used as a standard. No weight or measure may be manufactured or imported unless it conforms, except manufacture done exclusively for export or for scientific investigation or research.

Then the standards themselves. Section 9 deals with reference, secondary and working standards. They are as prescribed, and each must be verified and stamped in the prescribed manner on payment of the prescribed fee. One that is not verified and stamped is not a valid standard.

Finally, control at entry. Section 22 requires every person, before manufacturing or importing any weight or measure, to seek approval of its model from the prescribed authority, in the prescribed manner and on payment of the prescribed fee. Section 20 bars import of any weight or measure, even as part of a machine, unless it conforms to the Act's standards.

Key rules to remember

Metric basis of units: Every unit = metric system based on the international system of units (s. 4); No non-metric unit can be used as a legal unit of weight or measure.
Seven base units (s. 5): Length: metre | Mass: kilogram | Time: second | Electric current: ampere | Temperature: kelvin | Luminous intensity: candela | Amount of substance: mole; Learn the pairs in this order. Examiners ask for the list.
Standard weight or measure (s. 8): Conforms to standard unit + conforms to applicable s. 7 provisions = standard weight or measure; No manufacture or import of non-conforming ones, except for exclusive export or scientific research.
Valid standard (s. 9): Reference / secondary / working standard valid only if verified and stamped; Without verification and stamping it is not deemed a valid standard.
Model approval (s. 22): Approval of model required BEFORE manufacture or import; Two provisos: exemptions for certain items, and approval of models approved abroad.
Penalty for alteration (s. 26): Fine up to ₹50,000; repeat offence: imprisonment 6 months to 1 year, or fine, or both; Applies to tampering with standards or altering a weight or measure to deceive.

How to solve Metrology Units and Standards of Weights and Measures questions

Most questions on this topic ask you to state a rule, or apply it to a short fact situation. Use the same method each time.

1Identify what is being asked: unit, standard, or model approval.
2Name the provision in plain words and cite the section (4, 5, 7, 8, 9, 20, 22).
3For units, list the base units in full and state that they follow the metric system.
4For standards, state the three kinds and the verify-and-stamp requirement and the effect of non-compliance.
5For model approval, state who must seek it, when (before manufacture or import) and the exemptions.
6Apply the rule to the facts given, checking for any exception such as export-only manufacture.
7End with a clear one-line conclusion.

Quickest way: Section-to-rule map

When to use it: Use it for short-answer questions or when you have little time.

Link each section to one idea: 4 metric, 5 base units, 7 standard units, 8 standard weight or measure, 9 standards verified, 20 import, 22 model.
Write the rule in one sentence and add the section number.
Add the consequence: invalid standard, or no manufacture or import.
Check the facts for an exception, then conclude.

Common mistakes in Metrology Units and Standards of Weights and Measures

Listing fewer than seven base units or mixing in derived units like litre or newton.
Students recall everyday units instead of the section 5 list.
Fix: Memorise the seven pairs: metre, kilogram, second, ampere, kelvin, candela, mole.
Saying a reference standard is valid once it is made to specification.
Students forget the verification step.
Fix: State that section 9(2) requires verification and stamping, and 9(3) says otherwise it is not a valid standard.
Saying model approval is needed only for import.
The section is remembered loosely.
Fix: Section 22 covers both manufacturing and importing, and approval comes before either.
Claiming no exemption exists from model approval or from the conformity rule.
Provisos are skipped.
Fix: Recall the provisos: certain items like cast iron or carat weights and listed retail measures need no approval, and export-only or research manufacture is excepted from section 8(4).
Quoting the exact fees, tolerances or procedures as fixed in the Act.
Students assume the Act contains the detail.
Fix: Say these are prescribed by rules made under section 52.

Worked examples

Example 1

Krishna Instruments Pvt Ltd in Coimbatore wants to manufacture weighing scales for sale in India. It has not applied to any authority. Advise the company under the Legal Metrology Act, 2009.

Show the solution

Provision: section 22 says every person, before manufacturing or importing any weight or measure, must seek approval of its model in the prescribed manner, on payment of the prescribed fee, from the prescribed authority.
Facts: the company plans to manufacture scales for the Indian market and has not sought approval.
Exceptions: the first proviso exempts only certain items, such as cast iron, brass, bullion or carat weights, beam scales or specified retail measures. Unless its product falls in that list, no exemption applies. Manufacture solely for export would also be excepted under section 8(4) from the conformity rule.
Analysis: the product is for sale in India, so the company must first obtain approval of the model.

Answer: Krishna Instruments must seek approval of the model before it begins manufacture, paying the prescribed fee to the prescribed authority, unless its product falls within the proviso to section 22. Manufacturing without approval would breach the Act.

Example 2

State the base units under the Legal Metrology Act, 2009 and explain when a working standard is valid.

Show the solution

Units: section 4 requires every unit to follow the metric system based on the international system of units.
Section 5(1) fixes the base units: length, metre; mass, kilogram; time, second; electric current, ampere; thermodynamic temperature, kelvin; luminous intensity, candela; amount of substance, mole.
Specifications of base, derived and other units are as prescribed.
Working standards: section 9(1) says they are as prescribed.
Section 9(2) says each must be verified and stamped in the prescribed manner after paying the prescribed fee.
Section 9(3) says one not verified and stamped is not deemed a valid standard.

Answer: The seven base units are metre, kilogram, second, ampere, kelvin, candela and mole, all within the metric system. A working standard is valid only if it is as prescribed and has been verified and stamped in the prescribed manner on payment of the fee.

Exam tips

Write section numbers beside each rule. ICSI answers reward the provision first, then analysis, then conclusion.
Learn the seven base units as a table in your head so you can write them in under a minute.
Remember that detail like fees, tolerances and procedures is left to rules under section 52. Say so instead of guessing figures.
For problem questions, scan the facts for export-only manufacture or an item under the section 22 proviso.
Mention section 26 briefly if the facts involve tampering with a standard.

Practice questions from Legal Metrology

Metrology Units and Standards of Weights and Measures: frequently asked questions

What are the base units under the Legal Metrology Act, 2009?

Section 5 names seven: metre for length, kilogram for mass, second for time, ampere for electric current, kelvin for temperature, candela for luminous intensity and mole for amount of substance.

What happens if a reference standard is not verified and stamped?

Under section 9(3), it is not deemed a valid standard. Each reference, secondary and working standard must be verified and stamped in the prescribed manner after payment of the prescribed fee.

Is approval of model needed for every weight or measure?

Section 22 requires it before manufacture or import. The first proviso says it may not be required for certain items, such as cast iron, brass, bullion or carat weights and specified retail measures. The second proviso lets the authority approve models already approved abroad.

Can a non-standard weight or measure be imported?

No. Section 20 bars import of any weight or measure, alone or as part of a machine, unless it conforms to the standards established under the Act.