The Calex savings calculator calculates the amount of energy you can save by replacing lamps.
It is very easy to use. Enter the number of lightbulbs you would like to replace and fill in the wattage of the lamps. Submit the wattage of the new bulb next and estimate the average time you will have the lights turned on a day. The price per kWh is automatically assimilated on the national average price, but you can alternate this to your own energy price for a more accurate calculation.
If you additionally submit the purchase price of the replacement bulb, the calculator calculates the return on investment time for you.