LED Lighting Energy Savings Calculator
Switching from incandescent or halogen bulbs to LEDs cuts lighting electricity because an LED delivers the same brightness at a fraction of the wattage. This calculator works out the annual energy and cost savings from the wattage difference between your old and new bulbs. The saving equals the wattage gap, times the number of bulbs, times the hours used per day, times 365 days, divided by 1,000 to convert to kilowatt-hours, then multiplied by your electricity rate for the dollar saving. Usage hours and the electricity rate vary by household, so both are user-editable inputs. The comparison assumes the old and new bulbs produce equivalent brightness.
LED savings formula
Old kWh/yr = old W * bulbs * hours/day * 365 / 1,000
LED kWh/yr = LED W * bulbs * hours/day * 365 / 1,000
kWh saved = old kWh - LED kWh
Cost saved = kWh saved * electricity rate
Watts times hours gives watt-hours; dividing by 1,000 converts to kilowatt-hours. The comparison assumes both bulbs produce equivalent brightness in lumens.
LED lighting context
- An LED delivers the same lumens as an incandescent bulb at far lower wattage.
- Savings scale with usage hours: high-use fixtures repay the switch fastest.
- LEDs also last many times longer, cutting replacement cost not shown here.
- Compare bulbs of equivalent brightness for a meaningful wattage gap.
- ENERGY STAR certifies efficient LED bulbs and fixtures.
LED lighting savings: frequently asked questions
How much energy does switching to LED save?
The annual energy saved equals the wattage difference between the old and new bulb, times the number of bulbs, times the hours used per day, times 365, divided by 1,000 to convert watt-hours to kilowatt-hours. Because LEDs produce the same light at a fraction of the wattage, the saving per bulb can be large over a year.
How is the cost saving calculated?
Multiply the annual kilowatt-hours saved by your electricity rate in dollars per kilowatt-hour. The energy saving depends on usage hours, so a bulb left on all day saves more dollars per year than one used briefly. Enter your own rate and hours for an accurate figure.
Why compare wattage rather than brightness?
Brightness is measured in lumens, and an LED delivers the same lumens as an incandescent or halogen bulb while drawing far fewer watts. The savings come from that wattage gap for equivalent light output, so this calculator compares the input power of bulbs that produce similar brightness.
Do LEDs last longer too?
Yes. LED bulbs typically last many times longer than incandescent or halogen bulbs, reducing replacement frequency and cost. This calculator focuses on the energy and running-cost saving; longer life adds further value not shown here.
What usage hours should I enter?
Enter the average hours per day the lighting is actually on. Kitchen and living-area lights often run several hours a day, while a closet light runs minutes. The hours figure is a user-editable input because it varies widely by room and household.
Official sources
- U.S. Department of Energy: Lighting Choices to Save You Money.
- ENERGY STAR: certified lighting products.
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.