What This Calculator Does
The LED vs Incandescent Bulb Savings Calculator estimates how much electricity and money you can save each year by replacing traditional incandescent bulbs with energy-efficient LEDs. Because LEDs produce the same amount of light using a fraction of the power, the difference in wattage translates directly into lower running costs over time.
How to Use It
Enter the wattage of your old incandescent bulb (commonly 60 W) and the wattage of the replacement LED (often 8–10 W for the same brightness). Add how many hours per day the light is on, the number of days per year you use it, and your electricity price per kilowatt-hour. If you are switching several identical bulbs, increase the bulb count to see the combined savings.
The Formula Explained
The yearly saving is calculated as:
$$\text{Saving} = \frac{\text{W}_{\text{old}} - \text{W}_{\text{led}}}{1000} \times \text{hours} \times \text{days} \times \text{price}$$
Dividing wattage by 1000 converts watts to kilowatts. Multiplying by daily hours and days per year gives the kilowatt-hours (kWh) saved, and multiplying by your unit price converts energy savings into currency.
Worked Example
Suppose you replace a 60 W incandescent bulb with a 9 W LED, used 5 hours a day, 365 days a year, at $0.15 per kWh. The power difference is \(60 - 9 = 51\ \text{W} = 0.051\ \text{kW}\). Over a year that is $$0.051 \times 5 \times 365 = 93.075\ \text{kWh}$$ saved, worth \(93.075 \times \$0.15 \approx \$13.96\) per bulb per year.
FAQ
Does this include the bulb purchase cost? No — it only compares running (electricity) costs. LEDs also last far longer, adding further savings on replacements.
What electricity price should I use? Check your utility bill for the per-kWh rate. The calculator works in whatever currency you enter.
Why do LEDs use so much less power? LEDs convert most of their energy into light, while incandescent bulbs waste roughly 90% of it as heat.
