How much do your home’s holiday lights increase your power bill? Here’s the math.

Thanksgiving is over, which means it’s time to light up your house for the holidays.

Most people use holiday lights to make their homes festive for Christmas, but hanging bulbs that aren’t energy efficient could increase your electric bill.

Using LED light strands instead of incandescent lights is a great way to save money over the holidays, since LEDs use 70% less energy, according to the U.S. Department of Energy. LED lights are also sturdier than incandescent lights and last up to 40 times longer.

If you’re planning to hang lights for the holidays this year, here’s how much it will cost you.

Calculating the cost

Duke Energy calculates kilowatts per hour used in the area on an on-peak, off-peak and discount pricing system. The winter pricing began on Oct. 31 and runs through April 31.

Here are Duke Energy’s prices per kilowatt for the winter season:

• On-peak: 6-9 a.m. at $0.192297 per kilowatt hour

• Discount: 1-3 a.m. and 11 a.m.-4 p.m. at $0.060864 per kilowatt hour

• Off-peak: All hours that are not on-peak or discount hours at $0.084187 per kilowatt hour

To calculate the cost of your holiday lights, you’ll need to know:

• How many watts per bulb

• How many bulbs you’re using

• The number of hours you will run them

• The time-of-day rate that applies to each hour or set of hours

To calculate your kilowatt hours, you can use this formula: kWh=(watts per bulb × hours) ÷ 1,000, and multiply the kilowatt hour by the number of bulbs you’ll use for your total.

For example, based on Duke Energy’s winter rates, if you run 500 LED mini lights at .07 watts per bulb from 5-11 p.m. every day in December, it would cost roughly 55 cents. That total would be $3.13 if you used the same number of mini incandescent bulbs.

Customers can use Duke Energy’s Holiday Lighting Calculator to see cost estimates for your lights this year.

How to conserve energy while decorating your home

Here are some other ways you can conserve energy and save money on your electricity bill, according to Duke Energy:

• Use automatic timers to control the amount of time your lights are on

• Use smart strips to eliminate standby energy loss

• Hang shiny ornaments, tinsel, mirrors and other reflective items in place of lights to use less energy