On May 20 2019, the definition of the kilogram was revised. The new definition is based on the Planck constant. The value of Planck constant in the new definition was determined from the values of the Planck constant measured by several national metrology institutes over the world. In the revision, technologies to measure the Planck constant developed by the Mass Standards Group played a crucial role. The measurement technologies are presently used to realize the kilogram and disseminate mass standards which are used as technical basement to ensure reliability and international consistency of measurement in industrial and scientific fields.

1. Mass standards:
   The Mass Standards Group is realizing the kilogram based on the Planck constant and is disseminating mass standards to industry and scientific fields.

2. New mass measurement technology:
   The new definition of the kilogram will enable us to perform high-accuracy measurements of small mass in a sub-mg region, which is highly required especially in the filed such as innovative drug development and inkjet technologies. To realize the mass measurement in this range, the Mass Standards Group is focusing on the development of mass measurement technologies using a volt balance.

3. International Avogadro Coordination project:
   Silicon has three stable isotopes, ²⁸Si, ²⁹Si and ³⁰Si. A 5 kg 28Si-enriched single crystal was produced by the International Avogadro Coordination (IAC) project in 2006. The Mass Standards Group is carrying out research and development by using this enriched crystal as a member of the IAC project.

4. New density measurement technology:
   The Mass Standards Group is developing various accurate density measurement techniques, which are applied to density measurements for thin films required for characterization of coating materials and to density measurement of sea water required for climate change simulations.