Lumens measure how bright a light bulb is, so it is only important to know how many lumens a bulb produces if the primary lighting concern is brightness. The more lumens a bulb has, the more light it produces and a bulb with fewer lumens produces dimmer light. Lumens do not measure how much energy a bulb uses. It is still important to know how many watts a particular lighting fixture can accommodate, but lumens do not affect that criteria.
In mid-2011, the Federal Trade Commission required light bulb manufacturers to begin using new labels that inform consumers about a bulb's brightness, its estimated yearly operating cost, how long the bulb is expected to last, whether it provides warm or cool light, how much energy it uses and whether it contains mercury. The new label was intended to help consumers decide which bulbs were best for them at a time when compact fluorescent and LED bulbs were relatively new to the public.
Both Energy.gov and ENERGY STAR provide charts showing how many lumens a bulb should have based on the wattage a consumer is accustomed to purchasing. An example is a 75 watt bulb, which produces approximately 1,100 lumens of light.