On November 16, 2018, at the 26th meeting of the General Conference on Weights and Measures (CGPM), a resolution was adopted that introduced historical changes into the International System of Units (SI). This decision, effective from May 20, 2019, established that the SI units of measurement will be defined by means of a set of seven fixed numerical values of natural constants. The kilogram, the basic unit of mass, is no longer defined by a standard prototype, but relies on the Planck constant h. The definitions of the base SI units ampere, kelvin, and mole will also change. This will accomplish the long-term dream of scientists who have been claiming that measurement systems should be based on natural units. In this paper we derive the natural units as combinations of the seven defining natural constants and determine the numerical relations between the natural units and the units of SI.