Calculatium

Lighting Energy Cost Calculator

Calculate lamp energy use and variable electricity cost from lamp count, wattage, daily hours, days and your entered energy tariff.

Enter your values

The starting values are editable examples. Results update when you change your inputs.

Example: 5
Example: 10
Example: 4
Example: 30
Example: 0.2

Your result

Updates as you change your values.

Enter values to calculate.

How it is calculated

Energy in kWh = lamps × watts × hours per day × days / 1,000. Variable cost = kWh × price per kWh.

Worked example

Five 10 W lamps used four hours daily for thirty days consume 6 kWh. At EUR 0.20/kWh, their variable energy cost is EUR 1.20.

Before you calculate

Enter the electrical power drawn by each lamp, not an old bulb's equivalent brightness rating. Use a group of lamps with matching wattage and usage. Set the tariff to the variable energy price relevant to your comparison.

Interpreting the result

The estimate does not measure illumination quality or include fixed charges and taxes automatically. Dimming, controls and different usage schedules can change consumption. It is an energy-cost model rather than a lighting design.

Use the units shown beside each field. Monetary fields labelled EUR stay in euros; changing language does not exchange currencies. Results are estimates under the stated assumptions.