CFL savings calculator
Use this CFL savings calculator to figure out how much money you can save by installing compact fluorescent lights to replace incandescent lights.
The calculator assumes an average incandescent bulb lifetime of 1,000 hours and an average compact fluorescent bulb lifetime of 8,000 hours. You can change this if you wish based on the advertised lifetime hours of either the original or replacement bulb, or both.
For LED house lights, see my LED savings calculator.