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.

## Watts to lux calculation formula

#### Watts to lux calculation with area in square feet

The illuminance *E*_{v} 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 (ft^{2}):

*E*_{v(lx)} = 10.76391 ×* P*_{(W)}* *×* η*_{(lm/W)}* */* A*_{(ft}2_{)}

#### Watts to lux calculation with area in square meters

The illuminance *E*_{v} 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 (m^{2}):

*E*_{v(lx)} = * P*_{(W)}* *×* η*_{(lm/W)}* */* A*_{(m}2_{)}

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