Electric power in watts (W) to illuminance in lux (lx) calculator and how to calculate.
Enter the power in watts, luminous efficacy in lumens per watt, surface area in square feet / meters or spherical radius in feet / meters and press the Calculate button to get the illuminance in lux:
* the predefined luminous efficacy values are typical / average values.
The illuminance Ev in lux (lx) is equal to 10.76391 times the power P in watts (W), times the luminous efficacy η in lumens per watt (lm/W) divided by the surface area A in square feet (ft2):
Ev(lx) = 10.76391 × P(W) × η(lm/W) / A(ft2)
The illuminance Ev in lux (lx) is equal to the power P in watts (W), times the luminous efficacy η in lumens per watt (lm/W) divided by the surface area A in square meters (m2):
Ev(lx) = P(W) × η(lm/W) / A(m2)
