How Much Electricity Do Christmas Lights Use?

How much electricity Christmas lights use depends on two things: the total wattage of everything plugged in and how many hours it runs each night. A hypothetical 100-watt display running six hours a night for 30 nights uses 18 kilowatt-hours. At an example rate of $0.15 per kilowatt-hour, that works out to $2.70 in usage charges for the month.

Your display could land above or below that, which is why it’s worth five minutes with the actual numbers instead of guessing from the size of the house or how many colors you want. Here’s how to run the math yourself, with every assumption spelled out so you can swap in your own.

Start with the wattage of the lights you’ll actually hang

Start with the product’s power rating and check what that rating covers. Some ratings are for a single bulb. Others are for an entire string. If it’s per bulb, multiply by the number of bulbs. If it’s per string, multiply by the number of strings. Mixing these up gives an inaccurate estimate. Multiply a whole-string rating by the number of bulbs on that string and you’ll get a total that’s many times too high.

If your display mixes different kinds of lights, say larger bulbs along the roofline and mini lights in the shrubs, figure each group separately and add them together. If you want the cost of the whole display rather than just the lights, include any other plug-in decorations too.

Purely as an illustration: one group of lights totaling 80 watts plus another totaling 48 watts gives you 128 watts overall. Those are made-up figures to show the method, not ratings for anything in our inventory.

One more thing to know before you look up ratings. A name like C9 or C7 tells you the bulb’s size and shape, not its wattage. An LED C9 and an incandescent C9 can have a similar bulb form but different power ratings. Our bulb comparison explains why the bulb’s form and its lighting technology are two separate choices.

Turn watts and hours into kilowatt-hours

Your utility doesn’t bill you in watts. It bills in kilowatt-hours, which the U.S. Department of Energy describes as the measure of electricity used over time. Getting from one to the other takes two short steps:

Electricity used (kWh) = total watts × hours per night × number of nights ÷ 1,000

Estimated usage cost = kWh × your price per kWh

This is the same energy-estimation method laid out by Virginia Cooperative Extension, and it works for a strand of lights the same way it works for a space heater.

Take the 128-watt example from above. Six hours a night for 30 nights gives 128 × 6 × 30 ÷ 1,000 = 23.04 kWh. At the sample rate of $0.15 per kWh, that’s about $3.46 for those 30 nights, rounded to the nearest cent.

What a few sample displays would cost to run

Every row below assumes six hours per night, 30 nights, and $0.15 per kWh. The wattages are illustrative total loads for a whole display, and the rate is an assumption for the sake of the math, not a local average and not your plan’s price.

The schedule moves the number more than most people realize. Keep the same 100 watts and the same rate, and four hours a night for 30 nights uses 12 kWh and costs $1.80. Stretch it to eight hours a night and you’re at 24 kWh and $3.60. If you’d rather not pay to light an empty street at 2 a.m., set the display to run from dusk until the hour your neighbors have gone in for the night. That’s the simplest lever you have.

Use the rate on your own bill, and know what the number leaves out

Pull the price per kWh from your electricity plan or a recent bill rather than copying the sample rate. Convert cents to dollars before you multiply: 15 cents is $0.15, not $15.

What you’ve calculated is the charge tied to the extra electricity your lights consume. Fixed monthly fees don’t change because you hung lights. Tiered pricing, delivery charges, bill credits, and other plan terms can affect how much your actual bill moves, so check which charges on your statement vary with usage.

Operating cost is also a completely different number from an installation quote. It doesn’t pay for design, the lights themselves, mounting, installation, seasonal maintenance, removal, or storage. When we price a season, that price is based on the quantity of lights, including linear footage, and the style and location of the lighting. If you’re weighing leasing against buying your own lights, how leased Christmas lights work covers what happens to the lights after the season, including that they stay our property and go into our storage rather than your garage.

And one caution that matters for safety: an energy estimate tells you nothing about how many strings can safely be connected end to end or what a circuit can carry. Those limits come from the equipment ratings and the installation plan, not from a kWh figure.

A worksheet you can fill in

1. List each bulb or string type in your display and its wattage rating, noting whether that rating is per bulb or per string.
2. Multiply each rating by the matching quantity, then add the group totals together.
3. Decide how many hours per night the display will run and how many nights it will be up.
4. Multiply total watts × hours × nights, then divide by 1,000 to get kilowatt-hours.
5. Multiply the kWh by the price per kWh on your plan.

Write the assumptions down next to the answer. “18 kWh for 30 nights at six hours a night” is far more useful later than a dollar figure with no wattage or schedule behind it, especially if you decide to add a tree or shorten the hours next year.