Estimate the cost of a bank of LED lights
A resident has six identical 9 W hallway lamps on one switch. They want the cost of lighting the whole corridor, including evenings when guests stay late.
Open CalculatorInputs and calculation
| Tool input | Value |
|---|---|
| Currency | USD |
| Power unit | W |
| Power | 54 |
| Hours per day | 4 |
| Days or equivalent sessions | 30 |
| Duty cycle (%) | 100 |
| Energy price (USD per input kWh) | 0.3 |
54 ÷ 1,000 × 4 × 30 × 100% = 6.48 kWh. 6.48 × 0.3 rounds to USD 1.94.
Tool result · USD 1.94
| Tool input | Value |
|---|---|
| Currency | USD |
| Power unit | W |
| Power | 54 |
| Hours per day | 7 |
| Days or equivalent sessions | 30 |
| Duty cycle (%) | 100 |
| Energy price (USD per input kWh) | 0.3 |
54 ÷ 1,000 × 7 × 30 × 100% = 11.34 kWh. 11.34 × 0.3 rounds to USD 3.40.
Tool result · USD 3.40
What the comparison shows
Extra lighting adds 4.86 kWh. Total wattage is six times the rating of one lamp.
Assumptions and limits
Use electrical watts printed on the lamps or measured at the circuit. A bulb’s incandescent-equivalent rating describes light output.
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