${\displaystyle \mu _{0}=1.256~637~061~27(20)\times 10^{-6}~{\text{N))/{\text{A))^{2))$

4π × 10⁻⁷ N⋅A⁻² = 1.25663706143...×10⁻⁶ N⋅A⁻²

${\displaystyle \mu _{0}/(4\pi \times 10^{-7})=0.999~999~999~87(16)~{\text{N))/{\text{A))^{2))$

${\displaystyle \mu _{0}={\frac {1}{\epsilon _{0}c^{2))))$

${\displaystyle {\boldsymbol {B))=\mu _{0}({\boldsymbol {H))+{\boldsymbol {M)))}$

${\displaystyle {\boldsymbol {H))={\frac {1}{\mu _{0))}{\boldsymbol {B))-{\boldsymbol {M))}$

${\displaystyle {\boldsymbol {H))={\boldsymbol {B))-4\pi {\boldsymbol {M))}$