2018 Lighting Energy Cost Calculator

Light Bulb Cost Calculator

Estimate the electricity costs of a light bulb or light fixture. Enter the number and wattage of the lamps and the average amount of time they are on. Find out how much electricity the light fixtures in your home are using and also estimate the monthly cost per light fixture.

note: the average price per kWh is 12 cents

Estimate the cost savings and payback period for an upgrade to LED or CFL lamps (optional)


Lighting Energy Cost Estimate:

How to Estimate How Much a Light Bulb Costs

Light bulb electricity costs can be calculated by finding the kilowatt-hours a light bulb uses and multiplying by the cost per kilowatt-hour

Determine out how much it costs to keep the lights on by finding the total wattage of the light fixtures, multiplying by the hours the lights are used for and dividing by 1000, then multiplying by the cost per kilowatt hour charged by the electric company. The calculator above can simplify the process, but let’s go through the formula step by step.

Calculating the Total Wattage of a Light Fixture

Getting the total wattage of the lights to measure energy costs for involves adding the wattage of each bulb/fixture together to get the total. The average A19 incandescent light bulb uses 60 watts of electricity. If the wattage of each bulb is known, simply add the wattages of each bulb together to get the total watts for the lighting system. For example, five 60w incandescent light bulbs have a total wattage of 300w.

Calculating the Energy Used for Lighting

Estimating how much electricity lighting uses involves multiplying the total wattage from the previous step by the hours that the lights are on. To determine the monthly cost, multiply the wattage by the estimated hours the lights are on for the entire month. I find that it’s easiest to estimate how much time the lights are on for a given day and then multiply that by 30.

Find the kilowatt hours(kWh) used by dividing total wattage for the time period by 1000. For example, for five 60w light bulbs that are used 8 hours per day, the formula looks like this ((5*60) * 8) / 1000, or 2.4.

How Much Does That Electricity Cost?

Calculate the total lighting cost by multiplying the kilowatt-hours used by the cost per kWh. Continuing the previous example, the price would be 2.4 * .12, or $.29 per day or $8.70 per month. That’s almost $9 per month for five light bulbs. Use our electricity cost calculator to determine the actual cost of electricity usage.

Every electric company charges a different rate for electricity, and those rates may vary month to month. The national average cost for electricity is $.12 per kilowatt-hour. Find the exact rate charged on the electric bill sent by the power company.

How Much Money Can You Save Upgrading to LED Light Bulbs?

Calculate how much money LED and CFL lamps can save

You’re probably surprised by how much it costs to power an incandescent light bulb. Multiply that by an entire home full of lights, and you may be shocked by how much that costs per month.

Enter LED and CFL light fixtures. These light bulbs are becoming very popular for their energy savings and longevity, but they do cost more than an incandescent light fixture. The energy cost calculator can estimate how long it will take to pay for an LED/CFL upgrade based on the amount of usage, electricity costs, and the number of lamps needed.


In the past LED bulbs have had a poor reputation for bright or blue color temperatures and unnatural feel.

Modern-day LED bulbs are offered in a range of color temperatures from very cool in color to the warm glow of an incandescent that most are used to. Dimmable LED bulbs are also available.

An average LED light bulb that outputs the equivalent of the 60w incandescent fixture uses roughly 8-9 watts. Upgrading five light bulbs to LEDs using 9 watts of electricity would likely cost $1.30 to power for the month vs. the $8.70 of the incandescent lamps. That’s a significant cost savings.

LED lamps last significantly longer than incandescent lamps, meaning big savings by not needing to replace light bulbs every year or two. This is not as simple to estimate since light bulbs can last from 6 months to several years, but it’s obvious that over a lifetime an LED or CFL bulb pays for itself purely on replacement cost savings. The average LED bulb lasts 50,000-100,000 hours. A CFL light bulb lasts 25,000 hours on average.