Home Lighting Electricity Cost Calculator
Estimate daily, monthly, and annual lighting cost from bulb watts, quantity, and runtime.
Estimate home lighting cost
How this calculator works
This calculator treats a group of bulbs as one lighting load. For rooms with different bulb types or schedules, calculate each group separately and add the results.
The watts printed on an LED package are electrical input. The “equivalent watts” claim describes brightness relative to older incandescent bulbs and should not be used here.
Twenty 9-watt LEDs used four hours daily at $0.18/kWh cost about $0.13 per day and $3.89 per month.
How to get a more accurate estimate
- Use actual LED watts, not incandescent-equivalent watts.
- Separate outdoor, kitchen, and living-area groups when schedules differ.
- Use occupancy controls where lights are often left on unnecessarily.
Frequently asked questions
What wattage should I enter for an LED?
Use the small actual wattage printed on the bulb or package, such as 9W, not a 60W-equivalent label.
Does dimming reduce electricity use?
Compatible LEDs and dimmers usually reduce input as light output is lowered, though the relationship is not always perfectly linear.
Should outdoor lights be separate?
Yes, especially when they run dusk to dawn or use a different bulb wattage.
Results use the values you enter and the formula shown above. Real bills can include taxes, minimum charges, tiers, time-of-use pricing, cycling losses, and other adjustments. Use a recent bill or a plug-in energy meter when accuracy matters.