The Physikalisch-Technische Bundesanstalt (PTB) is the national metrology institute of the Federal Republic of Germany, responsible for scientific and technical services. It operates as a higher federal authority under the Federal Ministry for Economic Affairs and Climate Action. PTB's core tasks include determining fundamental and natural constants, realizing and disseminating the legal units of the International System of Units (SI), and conducting metrological research and development. It also provides calibration services and supports quality infrastructure globally.