Compare the cost of incandescent bulbs to compact fluorescent.
Type in your figures for an incandescent bulb and compare to a example CFL bulb:

 

Your incandescent:

Example entries for incandescent:

Comparable Compact Fluorescent

Wattage of lamp - Include Ballast:

watts

27 watts

Rated Lamp Life:

hours

750 7000 hours

$ Cost per lamp:

dollars

 0.75 $10.00

Cost of electricity per kWh:

dollars

 0.14

as entered

Number of lamps replaced:

   

lamp(s)

 1

as entered

  =   $

   savings

 $68.49 = Your savings over the life of new CFL lamp(s)
Result may vary by a few cents due to calculation method,