Enter the total power usage, average daily time, and the cost of electricity into the calculator to determine the cost per light.

Cost Per Light Formula

The following equation is used to calculate the Cost Per Light.

CL = P/1000*T*365*EC
  • Where CL is the cost per light ($/light/year)
  • P is the power consumption of the lightbulb (watts)
  • T is the average daily usage (hours)
  • EC is the electricity cost ($/kwh)

To calculate the annual cost per light, multiply the average daily usage by the power consumption, then again by 365 and the electricity cost, and finally, divide by 1000.

What is the Average Cost Per Light?


The average cost of a light depends on the power consumption, the electricity cost, and the average daily usage of the lightbulb. On average, a lightbulb can cost anywhere from $10.00 – $100.00 per year, depending on how often it is on.

How to Calculate Cost Per Light?

Example Problem:

The following example outlines the steps and information needed to calculate Cost Per Light.

First, determine the power consumption of the lightbulb. In this example, the power consumption is 50watts.

Next, determine the average daily run time. This light bulb is used 10 hours per day.

Next, determine the electricity cost. In this case, the electricity cost is $.40/kWh.

Finally, calculate the cost per light using the formula above:

CL = P/1000*T*365*EC

CL =50/1000*10*365*.40

CL = $73.00 /year