With LED technology, more light output (Lumens) can be achieved with less power (Watts). As technology improves, more Lumens will be produced using even less Watts. As a result, using Watts as a guide to brightness is no longer relevant. Lumens per Watt (lm/W) is a way to measure the efficacy of lights by measuring the total light output in Lumens divided by the power in Watts. The higher the Lumens per Watt (lm/W ) figure, the higher the efficiency and the lower the running costs.