Photometry Tools
Lux to Watts Calculator
Calculate required electrical power in watts (W) to achieve a target surface illuminance in lux (lx) over a given area.
Calculation Input
Required Power usage
0.00 W
Total Required Luminous Flux
0.00 lm
Heat Emission Ratio
Low Heat (10%)
Converting Illuminance directly to Electrical Power
To find the required electrical wattage to illuminate an area to a target lux level, we first find the total lumens needed (lux multiplied by area in square meters), and then divide that value by the bulb luminous efficacy ($\eta$):
$$P_W = \frac{E_{lx} \times A_{m^2}}{\eta}$$
Where $\eta$ is the light bulb efficacy. LEDs are approximately 6 times more efficient than traditional incandescent bulbs.