The National Physical Laboratory (NPL) is a premier scientific institution and India's National Metrology Institute (NMI), mandated by an act of Parliament to be the custodian of "National Standards" for measurement. Conceptualized in 1943 by the Governing Body of the Council of Scientific and Industrial Research (CSIR), its foundation stone was laid by Jawaharlal Nehru on 4 January 1947, making it one of the earliest national laboratories. The laboratory was established to solve the problem of ensuring uniform, accurate, and internationally traceable measurements to support post-independence industrial growth and scientific research.
As the NMI, the CSIR-NPL works by realizing, maintaining, and disseminating the seven base units of the International System of Units (SI), such as the meter and kilogram, and calibrating national standards of weights and measures. It is also responsible for maintaining the official Indian Standard Time (IST). Its role is anchored in the legal framework of the Standards of Weights and Measures Act, 1976, and its amendments. Internationally, it connects to the global measurement system as India became a member of the Metre Convention in 1957 and is a signatory to the Mutual Recognition Arrangement of the Bureau International des Poids et Mesures (BIPM).
Recently, the core mandate of maintaining measurement standards has remained, but its capabilities have been significantly upgraded. In January 2026, two apex-level calibration facilities were inaugurated: the National Primary Standard Facility for Solar Cell Calibration (NPF-SCC) and the National Environmental Standard Laboratory (NESL). The NESL, for instance, allows for the testing and recalibration of air pollution monitoring instruments under specific Indian environmental conditions, which were previously reliant on foreign certifications based on European or US weather profiles. The NPL is also actively working on developing futuristic quantum standards.