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Technical information on the proposed revision of the SI

For a brief discussion of how to define the base units of the revised SI from seven constants with fixed numerical values, we recommend:

Rapport BIPM-2018/02 by Richard Davis (BIPM)

The following diagrams as given in the SI Brand Book might also aid in explaining the relationships in the revised SI between the fundamental constants and the base units:

Base unit Conversion Diagram
second (s) 1 s = 9 192 631 770 / capital DeltanuCs
metre (m) 1 m = (c / 299 792 458) s = 30.663 318... c / capital DeltanuCs
kilogram (kg) 1 kg = (h / 6.626 070 15 x 10–34) m–2 s = 1.475 521... x 1040 h capital DeltanuCs / c2
ampere (A) 1 A = e / 1.602 176 634 x 10–19) s–1 = 6.789 686... x 108 capital DeltanuCs / e
kelvin (K) 1 K = (1.380 649 x 10–23 / k) kg m2 s–2 = 2.266 665... capital DeltanuCs h / k
mole (mol) 1 mol = 6.022 140 76 x 1023 / NA
candela (cd) 1 cd = (Kcd/683) kg m2 s–3 sr–1 = 2.614 830... x 1010 (capital DeltanuCs)2 h Kcd

Download all the diagrams as a zip file (high resolution)