In the beginning of 2025, the central government took a significant step with regards to the policy of ‘One Nation, One Time’. The Legal Metrology Division, Department of Consumer Affairs, Government of India, notified the Draft Legal Metrology (Indian Standard Time) Rules, 2025, with the objective of achieving precision in Indian Standard Time (IST) and its compulsory implementation across the country. This wide-ranging rule aims to make IST the standard time reference to be uniformly used across India. The government’s broader goal behind this initiative is to establish synchronisation of time across various sectors—Administrative, Legal, Financial, and Technological—thereby facilitating accurate time keeping and coordination nationwide.
Metrology is the scientific discipline concerned with measurement. It values the establishment, maintenance, and application of standardised units, ensuring the accuracy, reliability, and consistency of measuring instruments and systems.
Legal metrology refers to the enforcement of legal standards and regulations concerning measurements and measuring instruments, ensuring fairness, safety, and consumer protection in trade and public dealings.
Purpose of the Project
The project has been launched by the Department of Consumer Affairs, Government of India, in conjunction with National Physical Laboratory (NPL) and the Indian Space Research Organisation (ISRO). It focuses on disseminating IST with millisecond to microsecond accuracy, thereby ensuring precision in synchronisation. It will achieve this through a robust infrastructure centred around five legal metrology laboratories in different parts of India. Accurate time synchronisation is important for many key sectors today, such as, telecommunications, navigation, banking, power grid management, digital governance and scientific research, including gravitational wave detection and deep-space missions.
Presently, many telecom service providers (TSPs) and Internet service providers (ISPs) rely on foreign-based sources like Global Positioning System (GPS), which introduces cyber security risks and compromises strategic economy. The project addresses this vulnerability by mandating the adoption of IST for all time-dependent systems.
Indian Standard Time (IST) is based on the 82°30°’E longitude, which passes near Mirzapur in Uttar Pradesh. It is 5 hours and 30 minutes ahead of Greenwich Mean Time (GMT) or coordinated universal time (UTC).
The Prime Meridian at 0° longitude, passing through Greenwich, England, serves at the global time reference.
Since Earth rotates 360° in 24 hours—15° per hour or 1° every 4 minutes—countries set their standard time zones at intervals from this line.
India’s adoption of 82°30’ E ensures a uniform time across the country.
Framing of the Rules for Mandating IST
To develop a legally enforceable framework for synchronisation with IST, a high-level inter-ministerial committee was constituted. Chaired by the Secretary, Department of Consumer Affairs, the committee consisted of representatives from different key institutions, such as IIT Kanpur, NPL, National Informatics Centre (NIC), Indian Space Research Organisation (ISRO), Securities and Exchange Board of India (SEBI), Computer Emergency Response Team-India CERT-In along with the ministers from important departments of the government, including telecom, railways, and financial services, etc.
The committee’s mandate included drafting regulations under the Legal Metrology Act, 2009 laying down
- legal authorisation for nationwide IST adoption;
- guidelines for time synchronisation in digital and communication systems;
- strict frameworks for cyber-security and time-stamping; and
- examining if the project for IST dissemination is successfully implemented or not via modernised technologies and infrastructure.
Time Synchronisation Framework
According to the 2025 Draft Rules, using IST is mandatory. IST is 5 hours and 30 minutes ahead of UTC. Being the custodian of IST, the Council of Scientific & Industrial Research-National Physical Laboratory (CSIR-NPL) is responsible for maintaining and ensuring the traceability of IST to UTC. The rules describe the base unit of time—the second—as defined in the internationally accepted cesium-133 atomic clock standard. Time must be synchronised using Network Time Protocol (NTP) and Precision Time Protocol (PTP). Additionally, modern infrastructure including land-based time distribution systems and Navigation with Indian Constellation (NaViC) satellite signals will be used to enhance reliability, especially during outages or cyber incidents. The use of alternative time references is prohibited unless explicitly permitted. This is to ensure consistency and eliminate discrepancies that may arise from the use of unauthorised time sources.
Some Highlights of the Rules
- It is mandatory to adopt IST in all types of transactions, such as commercial, legal, financial, and administrative, being conducted all over India. IST will serve as the official time reference. This will not only remove timekeeping discrepancies but also enhance synchronisation across the nation with further uniformity and precision.
- The standard format for representing time is
- Date and Time: DD-MM-YYYY, HH:MM:SS;
- Time only: HH:MM:SS.
- IST must be displayed on all time-keeping devices used in all government offices and public institutions. Modern technologies, i.e., synchronisation protocols, like NTP and PTP will be used to ensure coordination of IST across all sectors.
- Although IST is to be used as the primary time reference, the other time zones could also be displayed for informational purposes. Note that these should be displayed along with IST and should be labelled properly.
- As time synchronisation requires the use of digital systems on a large scale, it is obligatory to use cyber security measures so that cyber threats like spoofing, jamming, and cyberattacks on time-synchronisation systems can be prevented.
- It is obligatory to use backup mechanisms such as NavIC signals and land-based time distribution systems. These are vital to be used during disruptions so that accuracy and reliability can be ensured. Besides, cyber-security measures and alternative reference mechanisms must be used so that resilience can be achieved.
- However, there are certain exceptions. In some special cases, such as in the fields of astronomy, scientific research and navigation, deviations from IST are authorised, but only after prior approval, and must conform to government-specified directives.
- A stringent system of compliance and periodic audits is clearly defined. This will ensure adherence to IST standards. Further, some advisories containing thorough standards for assessing accuracy in synchronisation and reporting systems will be published.
- Any violation of the rules will attract penalties, both in the form of fine and disciplinary action. The concerned officials under the Legal Metrology Act are authorised to lay down the penalties.
- Some additional guidelines and advisories will be issued by the central government to facilitate the enforcement of these rules. These will be regarding monitoring mechanisms, time synchronisation methods, and time accuracy standards.
- The mechanism for synchronisation, standards for accuracy, and guidelines for implementation have been specified. As a result, alignment with IST across the country is ensured along with promoting cyber security, operational efficiency, and improved governance.
- Emergency response coordination has been strengthened; accurate financial transactions are enabled; and regular scheduling of public transportation is ensured. Further, consistent time standards are formed for documentation and record-keeping purposes, thereby providing legal and regulatory compliance.
- Industrial operations will benefit from improved technological integration, synchronised manufacturing methods, and higher global competitiveness.
- Accurate record-keeping will be enabled and an important mechanism for synchronising national infrastructure and communication networks will be delivered efficiently.
World Metrology Day 2025: India’s Observance and Contributions
The Department of Consumer Affairs, Government of India, commemorated World Metrology Day 2025, marking the 150th anniversary of the Metre Convention, signed in Paris on May 20, 1875. This historic agreement laid the foundation for the metric system, enabling global uniformity in measurement standards. It is noted that India joined the Metre Convention in 1957 following the enactment of the Standards of Weights and Measures Act, 1956.
Initiated in 1999 by the International Committee for Weights and Measures (CIPM), the observance celebrates the vital role of metrology in science and society. The theme for 2025, Measurement for all times, for all people underscores the enduring relevance of measurement—from the past to the future—across all walks of life.
Conclusion
The Draft Legal Metrology (IST) Rules, 2025 are a significant step in revolutionising time management in India. With these rules, enforcement activities and administrative functioning of the government will be carried out efficiently, accurately, and in coordination. Important sectors such as telecommunications, banking, 5G technologies, artificial intelligence, and Internet of things will have improved precision. The implementation of these rules will not only ensure uniformity in time keeping across various sectors but will also give way to technological advancement, economic efficiency, and strategic security.
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