• The specification center beam candlepower measures intensity of light at the bulb's centerULTRA.F/Stockbyte/Getty Images
  
  Light-emitting diode (LED) lighting involves the use of a semiconductor diode. Upon the receipt of voltage, or electric current, the diode emits light. LEDs uses include residential, commercial and automotive. Like all lighting bulbs, whether incandescent, halogen or any other type, certain specifications provide a means of rating and comparing various LED bulbs.
  
  

Initial Lumens

• A unit of measurement for light, a lumen represents the amount of light produced by a bulb. Initial lumens measure the amount of light the bulb generates when new, since all bulbs gradually lose light function over time. A General Electric (GE) Par20 LED bulb has a rating of 200. A GE Par30 floodlight bulb rates from 320 to 340. According to GE, lumens ratings only give one part of a bulb's worth and must be considered along with center beam candlepower (CBCP) -- the amount of light at the center of the bulb. Although a bulb with a higher initial lumen generates more light, that light may be wasted compared to a bulb with a higher CBCP as it focuses more of its light on its intended target, thus offsetting the lesser lumens.
  
  

Watts

• Watts refer to the amount of power consumed by a light bulb. Traditional incandescent light bulbs carry watt ratings such as 100-watt bulbs and 60-watt bulbs. LED bulbs are much more energy efficient so the number of watts is much less. Touch both bulbs while illuminated and the difference is apparent, as incandescent light bulbs get very hot while LED bulbs stay cool, thus losing far less heat. For example, according to Low Impact Living, LED bulbs pull as little as two watts, which is the equivalent of 10 to 15 watts for an incandescent bulb. By contrast, GEPara 20 is 7 watts and Para30 10 watts.
  
  

Rated Life

• Every manufacturer lists, as a specification of its LED bulbs, a number in hours that represents how long the bulb will last under normal use. This specification, known as rated life, for the GEPara 20 and Para30 is 30,000 hours based upon 70 percent lumens, which means at the end of those hours the light will be 70 percent as bright as it was at the onset.