Quantity
Symbol
Formula
Value
Unit
Differencea %
Six initial fundamental constants: 
structural constant of atoms
b
8.278692517066260
1
unknown
speed of light in vacuum
299 792 458
m×s−1
0.000
elementary charge
1.6021766208 ´ 10−19
A×s
0.000
mass of electron
9.10938356 ´ 10−31
kg
0.000
mass of proton
1.672621898 ´ 10−27
kg
0.000
pi; Archimedes’ constant
or Ludolph’s number
c
3.141592653589793
1
0.000
Other 12 (without e, redundant 11) constants (derived from 6 initial fundamental constants): 
inverse fine-structure constant
137.073499584258
1
+0.027d
fine-structure constant
0.0072953561637514
1
−0.027d
von Klitzing constant
2.581987123285 ´ 104
W
+0.027d
action constantA0; Planck’s h
6.627883290240 ´ 10−34
J×s
+0.027d
conversion constant
1.208 663875508 ´ 1014
Hz×V−1
unknown
ratio e/h; ratio e/A0
2.417327751017 ´ 1014
Hz×V−1
−0.027d
Josephson constant
4.834655502034 ´ 1014
Hz×V−1
−0.027d
elementary charge
; Intial fundam.const.
1.6021766208 ´ 10−19
A×s
0.000
Rydberg constant
1.09647274840335 ´ 107
m−1
−0.082d
Bohr radius
5.294668730599 ´ 10−11
m
+0.055d
Bohr magneton
9.276547861521 ´ 10−24
A×m2
+0.027d
nuclear magneton
5.052165865121 ´ 10−27
A×m2
+0.027d