LED light efficiency is measured in terms of lumens per watt—the amount of light produced for each watt of electricity consumed. More lumens per watt means more light for your money. If you compare the raw lumen output of conventional lamps with the lumen output of many LED lighting fixtures, it often seems that LED fixtures deliver less light than the conventional alternatives. Such comparisons, however, are inaccurate and misleading, as they fail to account for the significant amount of wasted light in conventional lighting solutions.
Simply put, lumen output is a poor measure of the suitability of a lighting fixture for a given task. A better measure is delivered light — how much light a fixture delivers to a surface or area, as measured in lux (lx) or foot candles (fc). You can make accurate comparisons between conventional and LED lighting fixtures on the basis of delivered light, as it measures how much of a light source’s raw lumen output reaches a surface or area you want to illuminate.