How Much Do Lights Affect an Electric Bill?

Rising energy costs or the loss of a job can cause you to examine your habits at home in an effort to reduce your power bill. Lights are among the most frequently used electrical items in your home, so when trying to reduce your bill it is important to understand what type of impact your light bulb usage has on it.

Types of Bulbs

Compact fluorescent bulbs (CFLs) can help reduce your electric bill.

The type of light bulbs you use in your home can have an impact on your electric bill. Incandescent bulbs are the most expensive bulb to run. These bulbs require a higher amount of energy, which results in a higher level of power use in the home. A compact fluorescent (CFL) bulb typically requires about 75 percent less power than incandescent bulbs, which helps reduce energy use. Light-emitting diode (LED) bulbs require about half the energy of the CFL bulb, making them the most energy-efficient option with the highest potential of lowering your bill.

Length of Use

The myth that light bulbs -- especially fluorescent light bulbs -- require more energy to turn off and on than they do to run consistently makes some people hesitant to turn lights off when they are going to return shortly, only to turn them on again. While some light bulb types do require a higher amount of energy to turn on, the increased amount of energy usage is only for a fraction of a second and does not have a big impact on your electric consumption. Therefore, if you will return within 15 to 20 minutes, it is okay to leave the light on. However, if you will be gone longer, turn it off because you will save more energy than you will use re-lighting the bulb.

Calculating Energy Use

If you want to calculate how much you can save on your electric bill based on the type of light bulbs you use, a simple formula can give you an idea of your potential savings when using different bulbs. Each light bulb comes with a wattage rating. If you burn a bulb for one hour, divide the wattage number by 1,000. That is the amount of energy in kilowatt hours the bulb uses in one hour. Multiply that number by the cost of electricity in kilowatts per hour as charged by your utility company. This tells you how much it costs to run that bulb for one hour. For instance, a 60-watt bulb burns 0.06 kilowatts per hour. If your electric company charges 10 cents per kilowatt hour, burning the bulb for an hour costs $.60.


One of the reasons some people choose not to purchase light bulbs that are more energy efficient is the cost of the bulbs. CFL bulbs are more expensive than incandescent bulbs. Likewise, LED bulbs are much more expensive. You can calculate the expense of running each bulb per hour and compare them to decide if the extra cost is worth it. However, you must also take into account that both CFL and LED bulbs have a longer life than incandescent bulbs. Therefore, you do not need to buy them as often. So you must also calculate how much per year you would spend on light bulbs for each type, based on their typical life span. For instance, an incandescent bulb has about 1,500 hours of life. CFL bulbs last around 10,000 hours, and LED bulbs can last up to 50,000 hours.

About the Author

Kimberly Turtenwald began writing professionally in 2000. She has written content for various websites, including Lights 2 You, Online Consultation, Corpus Personal Injury and more. Turtenwald studied editing and publishing at Wisconsin Lutheran College.