While not nearly power-hungry as appliances like air conditioners or washing machines, it can be helpful to know how much electricity a light bulb uses when you're looking at your whole home's energy usage.
Generally, light bulbs use between 2 and 100 watts (W) of electricity, depending on the size and type. Traditional incandescent bulbs use 25 to 100 W, and LED bulbs use 2 to 18 W. Light bulbs draw around 110 volts and usually less than 1 amp.
How much you use your light bulb has the biggest impact on how much electricity it uses over time – on average, lights are on for about 2 hours per day in U.S. homes. Taking an average 60 W incandescent light bulb:
Using your light bulb for 1 hour per day results in 0.42 kilowatt-hours (kWh) of electricity per week, 1.83 kWh per month, and 21.9 kWh per year.
Two hours per day of light bulb usage comes to 0.84 kWh per week, 3.65 kWh per month, and 43.8 kWh per year.
On the upper end, running a light bulb for 3 hours per day uses 1.26 kWh of electricity per week, 5.48 kWh per month, and 65.7 kWh per year.
With a more energy efficiency LED light bulb (averaging 10 W), here's what your energy usage could look like:
Using an LED light bulb for 1 hour per day results in 0.07 kilowatt-hours (kWh) of electricity per week, 0.30 kWh per month, and 3.65 kWh per year.
Two hours per day of LED light bulb usage comes to 0.14 kWh per week, 0.61 kWh per month, and 7.30 kWh per year.
On the upper end, running an LED bulb for 3 hours per day uses 0.21 kWh of electricity per week, 0.92 kWh per month, and 11.0 kWh per year.
Don't forget – it's pretty rare that you just use a single light bulb when you turn on the lights. You can take any of the numbers above and multiply them by the number of light bulbs you might turn on in a room or throughout your house to get a more realistic estimate of energy usage.
Different wattage light bulbs use different amounts of electricity over the course of a year. Assuming you keep a light bulb on an average amount (2 hours per day, adding up to 730 hours per year), here's how much electricity you'll use over the course of a year for different wattage individual light bulbs, both incandescent and LED:
How many watts do incandescent light bulbs use in a month and a year?
How many watts do LED light bulbs use in a month and a year?
Something jumps out right away: you can see pretty clearly how much energy newer LED bulbs save.
We'll mostly be referring to the electricity used by light bulbs in terms of kWh in this article. The reason is simple: your electric bill is measured in kWh, and you get charged based on the kWh of electricity you use per month!
When you get your monthly electric bill, you only see the total amount you're charged, not how much each appliance contributes to your final bill. Based on an average wattage of 60 W for incandescent light bulbs (amounting to 43.8 kWh/year) and an average wattage of 10 W for LED light bulbs (amounting to 7.3 kWh/year), here's how the cost to run a light bulb pans out over the course of a month and a year using state average electricity rates:
Monthly and yearly costs to power an incandescent light bulb by state
Note: average electricity rates are based on October 2021 data from the U.S. Energy Information Administration (EIA).
Monthly and yearly costs to power an LED light bulb by state
Note: average electricity rates are based on October 2021 data from the U.S. Energy Information Administration (EIA).
Looking to offset your electric bills (and the energy these appliances use) with solar? When you sign up (for free!) on the EnergySage Marketplace, you can compare solar quotes from high-quality, local solar installers. Make sure to keep in mind your current and future electricity usage, and talk about how that could change with your installer for the most accurate quotes.
Calculate how much energy your own light bulb uses
If you want to know how much electricity your light bulb uses (or at least is supposed to use), take the estimated yearly electricity use in kWh – this is probably your best bet for an accurate number. Simply multiply this number by the average electricity rate in your area to get an estimate of how much you spend to power your light bulb each year. For an estimated monthly cost, divide the estimated yearly cost by 12.
What's the best time to run a light bulb?
If you're on a time-of-use (TOU) rate plan, you are charged different amounts for electricity throughout the day. In general, it's cheaper to use appliances during "off-peak" hours, which are usually overnight. This isn't ideal for light bulbs, but given how inexpensive it is to power them generally, it's probably not worth worrying about.
What size battery do you need to back up a light bulb?
All popular home batteries can power a light bulb: most lithium-ion batteries like the Tesla Powerwall or Generac PWRcell have a power rating of 4 to 5 kW or higher and 10+ kWh of usable capacity. Light bulbs use about 60 W (0.06 kW) of power at any one time, meaning a battery will be plenty suitable for backing up and powering a bunch of light bulbs, even for long periods of time.
How many solar panels does it take to run a light bulb?
On average, light bulbs use about 60 W of electricity to stay powered. With solar panels rated at around 350 W, you'll be able to power a light bulb with a solar panel easily.
What are ENERGY STAR appliances?
ENERGY STAR is a U.S. government-backed system that certifies how energy-efficient appliances are. If an appliance is better than the average appliance in its category by a certain amount, it is labeled as "ENERGY STAR certified." ENERGY STAR appliances cost less money to run, given that they are more efficient with the electricity they use.
Solar savings vary widely, and your unique savings depend on factors like electricity usage, location, and electric rates and plans. In general, most homeowners can expect to save somewhere between $10,000 and $30,000 over the lifetime of a solar panel system. On average, it takes between 7 and 8 years for most homeowners who shop for solar on EnergySage to get their solar panels to pay for themselves.
Going solar is one of the most effective ways to reduce or eliminate your electric bill, and you should make sure you are getting several quotes from reputable installers before you decide to move forward. Visit the EnergySage Marketplace to get solar quotes from installers in your area and begin comparing options.
