Electricity basics
How to Compare LED Bulb Electricity Costs
Compare bulb electricity at matching brightness. Use actual input watts, daily hours, bulb count, and price difference rather than equivalent-watt labels.
Compare actual input watts at the brightness you need. Multiply the watt difference by hours, bulb count, and your rate. Equivalent incandescent watts are not LED input watts.
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An LED package may show both its actual watts and an incandescent-equivalent number. Use actual input watts to estimate electricity. The equivalent number helps describe a brightness comparison, not the LED's power draw.
The FTC's bulb-shopping guide explains that lumens describe brightness and watts describe power. Match the lighting need before comparing operating costs.
Compare a suitable light output
Check lumens, color appearance, fixture compatibility, and any dimmer requirements. A lower-power bulb that provides insufficient light is not a like-for-like replacement.
Read instructions for enclosed fixtures, damp locations, and special fittings. Do not assume that every LED works in every fixture or dimmer. Follow the product's approved uses.
Record the exact actual wattage. If the package says “60 W equivalent” and lists 9 W input, use 9 in the electricity calculation, not 60.
Calculate energy for one bulb
Suppose a hypothetical 9 W bulb operates five hours daily. It uses 9 ÷ 1,000 × 5 = 0.045 kWh per day.
At an illustrative $0.20/kWh, electricity costs $0.009 daily. Over 365 identical days, that is about $3.29. A daily cost can look tiny while the annual total remains worth comparing.
The EIA electricity guide supports the watts-to-kWh conversion. Keep unrounded energy in the calculation and round currency at the end.
Compare two example wattages
Imagine a suitable 60 W bulb and a suitable 9 W bulb providing the desired light. Their hypothetical power difference is 51 W.
At five hours daily, annual energy difference is 51 ÷ 1,000 × 5 × 365 = 93.075 kWh. At $0.20/kWh, the annual electricity difference is about $18.62 per bulb.
For six bulbs on that same schedule, the difference is about $111.69 per year. Use your own bulb count and schedule in the same calculation. If actual hours are shorter, the saving falls proportionally.
Include purchase and use differences
If the lower-power option costs an extra $4 per bulb in this example, simple electricity payback is about 0.21 years. That calculation excludes bulb failures, labor, dimmer changes, and other costs.
Do not assume a stated lifespan will be achieved in every fixture. Check product guidance and warranty terms. A difficult-to-access fitting can make replacement effort matter separately from electricity.
For smart lighting, include relevant standby draw when comparing full ownership energy. Do not silently treat every connected bulb as zero consumption when its light is off.
Record the comparison clearly
- Match the required brightness and approved fixture use.
- Record actual input watts for both choices.
- Use realistic hours for each room.
- Multiply by the number of bulbs on that schedule.
- Compare electricity savings with the relevant extra cost.
Calculate rooms separately if their use differs. Kitchen bulbs and rarely used closet bulbs should not share an invented daily schedule.
Use the electricity calculator for each stated load. For several identical bulbs, enter their combined watts or multiply the energy result by the bulb count.