Customary Units Permitted Alongside SI Units Under Legal Metrology Act, 2009: Key Advisory Explained
Background and Context
The Department of Consumer Affairs, operating under the Ministry of Consumer Affairs, Food and Public Distribution, has issued an important advisory clarifying the legal position regarding the use of traditional and customary units of measurement in trade and commerce. The advisory, bearing reference I-9/1/2026-W&M Section, was issued from Krishi Bhawan, New Delhi, dated 18th May 2026, and is addressed to the Controllers of Legal Metrology across all States and Union Territories.
This clarification becomes particularly significant given the widespread practical usage of units such as inches, feet, square feet, yards, and dozen across multiple sectors of industry, retail, real estate, and everyday commerce — even though these do not form part of the legally mandated measurement framework under Indian law.
The Core Legal Framework: SI Units Remain Supreme
Under the Legal Metrology Act, 2009 and the Rules framed thereunder, all units of weight and measure prescribed for use in India are anchored in the metric system and the International System of Units (SI units). This framework ensures uniformity, accuracy, and consumer protection across all commercial transactions and regulatory processes.
The advisory unequivocally reaffirms that SI metric units shall continue to hold the status of legally recognized standard units for every purpose — whether for trade transactions, regulatory compliance, or consumer protection. No customary or non-SI unit can replace or override this standard.
Important: The primacy of SI units under the Legal Metrology Act, 2009 is non-negotiable. Any supplementary declaration using customary units must strictly operate as additional information and never as a substitute for the mandatory SI unit declaration.
What Has Been Permitted: Supplementary Use of Customary Units
While the law remains firm on SI unit primacy, the advisory introduces a pragmatic accommodation. The Department has clarified that customary units may be used as supplementary or additional statements alongside mandatory SI unit declarations, subject to specific conditions being met.
This permission acknowledges the ground reality of Indian markets and international commercial practices where units such as feet, inches, square feet, and dozen are deeply embedded in trade terminology and consumer comprehension.
Conditions for Permissible Use of Customary Units
The advisory lays down four clear conditions that must be satisfied for supplementary customary unit declarations to be lawful:
Prominent Display of SI Units: The standard SI unit, as prescribed under the Legal Metrology Act, 2009 and applicable Rules, must be declared prominently. The SI declaration must be clearly visible and must not be overshadowed by the customary unit reference.
Supplementary and Non-Substitutive Nature: The customary unit may only serve as additional informational content. It cannot function as a replacement or equivalent alternative to the mandatory standard unit declaration.