Cost

• LED bulbs have low wattages, from 0.15 to 1 watt. A 1-watt bulb is very bright. Strings of LED Christmas lights use 1 to 3 kilowatt hours of energy compared to incandescent, which used 12 to 105 kilowatt hours in Consumer Report tests.
  
  

Energy Tests

• In December 2007, Consumer Report tests showed it cost $1.30 to operate conventional mini lights for 300 hours compared to 30 cents for LEDs. The cost for 50-foot strings of C7 incandescent lights was $8, while LEDs cost 14 cents. Regular C9 holiday lights cost $11 to operate; LEDs cost 14 cents.
  
  

Durability

• Consumer Reports' tests found LEDs worked for 4,000 hours; incandescent bulbs burned out after 2,000. The plastic cover on LEDs is less likely to break than the glass in incandescent bulbs.
  
  

Retrofit LEDs

• Power-saving retrofit LED bulbs save even more by fitting into C7 or C9 Christmas light sockets to replace incandescent bulbs. LED retrofits are more efficient. Their power goes to produce light. Up to 90 percent of an incandescent bulb's energy is used to produce heat.