watt per square metre

Name	Symbol	Quantity	Base units
watt per square metre	W/m²	heat flux density, irradiance	kg s⁻³
The watt per square metre, symbol W/m², is the SI coherent derived unit of heat flux density, and irradiance.
Definition			h c⁻² Δν_Cs⁴
$1 \mspace{4mu} \text{W} / \text{m}^2 \mspace{6mu} = \dfrac{(299 \mspace{4mu} 792 \mspace{4mu} 458)^2}{(6.626 \mspace{4mu} 070 \mspace{4mu} 15 \times 10^{-34})(9 \mspace{4mu} 192 \mspace{4mu} 631 \mspace{4mu} 770)^4} \mspace{6mu} \dfrac{h \mspace{4mu} {\Delta \nu _{Cs}}^4}{c^2}\\ \\ \\ 1 \mspace{4mu} \text{W} / \text{m}^2 \mspace{6mu} \approx 1.899 \mspace{4mu} 441 \mspace{4mu} 492 \mspace{4mu} 889 \mspace{4mu} 243 \mspace{4mu} 145 \times10^{10} \mspace{6mu} h \mspace{4mu} c^{-2} \mspace{4mu} {\Delta \nu _{Cs}}^4$