Convert luminous efficacy between lumen per watt and relative luminous efficiency (%).
Luminous efficacy measures how many lumens a source produces per watt of energy consumed (lm/W). Relative luminous efficiency, in percent, compares that value with the theoretical maximum of 683 lm/W (monochromatic light at 555 nm, to which the eye is most sensitive). Select the units and enter a value. For example, a 100 lm/W lamp has a relative efficiency of about 14.6%.