How To Measure and Install Christmas Lights

How To Measure and Install Christmas Lights

There’s nothing better than driving down the street and seeing beautiful Christmas light displays. There’s always the question of when the best time to hang Christmas lights, as well as what’s the best way to accurately estimate how many Christmas lights you will need. The best time for hanging Christmas lights is before the weather gets cold. The perfect moderate temperatures are right after Thanksgiving, even if you don’t turn them on for a couple of weeks after installation. 

Before beginning to measure, walk to the street, and look at the house how others would see your house. Identify the areas of the house where Christmas lights will make the most impact when seeing the house from the street. This will minimize over-purchasing Christmas lights, keep you on-budget, and maximize the usefulness of the lights that are hung on your home.

Measuring Your Home

Tools Needed

  • Tape Measure
  • Pencil and paper or phone with a note app
house with arrows showing measurement pattern
Original image source: Sure Thing Home Inspections

For this example, I am using the front of the house in the above picture as the intended focal point of the Christmas lights. Notice the red lines on the front and side of the house- this is the pattern that you will follow on the ground. The reason I recommend eyeballing the start and end location of each section of the roof and measuring on the ground is because a couple of inches more or less won’t make a difference and it is a lot safer method than setting up a ladder on grass, measuring some and repeating for each section of the roof.

Start at one side and lay the tape measure on the ground with the beginning at the starting point for the lights (see #1 in the picture) and stop at the edge where the tape measure will need to be moved to the next starting point. Write down the first distance and move the beginning of the tape measure to the next point (#2). Write the distance and continue with each new area until all areas that need Christmas lights are done.

Now that you know you will need however many feet of Christmas lights, you can feel confident going to the store and buying that amount of lights. Keep in mind that Christmas lights generally come in 25, 50, and 100ft lengths; if your measurement comes up to a total of 212 feet, purchase 225 feet to ensure you have enough.

Pro Tip


If you want that perfect amount of lights for the run of lights and don’t want the overage of lights to show, use small strips of electrical tape to cover whichever lights you don’t want to have illuminated. The tape easily comes off when you want the individual lights to shine.

Which Type of Lights Should I Buy?

If you know what you want, skip ahead to Hanging Christmas Lights in the next section. If not, there are two popular types of Christmas lights: Incandescent and LED. Which one you buy depends on what you want to accomplish, and the two are described below.

Incandescent Lights

incandescent bulb glowing

Incandescent Christmas lights have incandescent bulbs in a string. They come in many different shapes and sizes, from mini T5 bulbs up to giant G40 globe bulbs.

Incandescent bulbs produce light by passing an electrical current through a filament. The filament slowly wears every time the lights are used, so they will burn out at an average of 3,000 hours of use. They consume a large amount of energy compared to LED, and due to the energy requirements, 25-foot strands can only be chained up to 36 strands long. Care should be taken when handling the bulbs, as they are made of glass and break easily.

Even though the industry has changed how they measure the brightness of bulbs, incandescent bulbs are still rated in watts (the new standard is lumen). While not an accurate measure of the brightness of bulbs, you can follow this old rule for purchasing incandescent bulb strands- the higher the watts, the brighter the bulbs.

LED Lights

led string of christmas lights

LED Christmas light bulbs use a semi-conductor and a diode that is designed to emit light when current passes through it. This is much more efficient than incandescent bulbs using resistance to make a filament produce light. 

 LED Christmas lights are an average of 70% more efficient than incandescent bulbs. This equals an average of 25,000 kilowatt-hours (kWh) over the life of the bulbs, which is 7% of the average kWh usage of 350,000kwh for the same usage time of 3,000 hours. When comparing wattage use to lumen output, LED T5 bulbs consume an average of 0.07 watts per lumen of light output, whereas incandescent consumes 1watt for every lumen output.

It may seem like I am against incandescent, but I appreciate the look of classic incandescent bulbs. What I do not like about them is the energy usage. When the technology is available to reduce my energy usage and carbon footprint (as well as save money), I am excited to use the technology.

Hanging Christmas Lights

Important Info


Always remember to practice proper electrical safety. Do not handle Christmas light strands while plugged into an outlet, and do not attempt to troubleshoot non-working bulbs while strand is plugged into an outlet. Before climbing a ladder, read the instructions and ensure the ladder is on the proper side (if it’s an extension ladder) and is securely placed on the ground.

Tools and Equipment Needed

  • Ladder
  • Strand Clips
  • Tape Measure
  • Extension Cords
  • Nails or Screws (if not using strand clips)
  • Hammer or staple gun (if not using strand clips)
man holding giant ball of lights

Now that you’ve measured and purchased lights (or pulled some strands out of storage), gather all the items you need from the list above. Depending on the height where lights will be hung, an A-frame or extension ladder can be used.

Pro Tip


When using an extension ladder, first read the instructions on proper setup. After extending the ladder out, stand with your toes touching the edges of the base of the ladder. Stick your arms straight out at shoulder height parallel to the ground. If your hands cannot grip the sides of the ladder while your arms are straight, readjust the ladder until they do. Then double-check that you can read the sticker with the beginning of the brand name pointed towards the ground. If it’s not, the ladder should be flipped over to the proper side. If yours doesn’t have the label, then follow the directions of the label on the ladder.

Test Light Strands

This may seem silly to do with new strands, but test every strand (new or not) before hanging them. Strands could have bad bulbs or not work at all. I’ve gotten a box home, opened it, and realized they were used and got restocked on the store shelves. Of course, that strand didn’t work.

Most LED strands are wired in parallel with the exception of the end bulbs. If your strand has replaceable LED bulbs, take a look at the color of the base of the end bulbs versus the rest of the bulbs. Generally, the end bulbs will be a different colored base, indicating those bulbs are different and need to go in those spots for the strand to work properly. Don’t swap these with different colored bases if you want the strand to work. Incandescent strands are dependent on the manufacturer, and there’s no easy way to tell on older strands other than removing a bulb or two and seeing if the rest of the strand stays lit.

Christmas Light Clips

christmas light clips
source: triachnid

These are incredible. Gone are the days of screwing, stapling, and nailing lights to the house. Nylon Christmas light clips come in a variety of sizes to fit most Christmas light bases. There are different types of clips for attaching lights to trees, shrubs, gutters, roofs, shingles, walls, etc. There are even magnetic clips to attach to metal surfaces. At between $0.15- $1 apiece, these are a more expensive option than staples but are easier to remove at the end of the season; the time and hassle saved pays the return on investment.

Light clips are very easy to use. Insert the base or wire through the small end of the holder and push the flat end over the gutter or shingle. Tree and shrub clips are like a wire tie- wrap the clip around the branch and wire, then twist the top. If there is excess at the end of the strand, spare lights can be covered with electrical tape, and excess wire can be looped and hidden with a clip. Any spots that can’t use clips can have staples, nails, command strips, or zip ties applied to hold the wire.

How Many Light Strands to Connect Together?

Pro Tip


When connecting strands together end-to-end, it does not matter whether the bulbs are LED or incandescent- math will need to be done. The average United States home outlet is 15 amps. The Underwriters Laboratories (UL) mandates that if the wire used is 22-gauge, a maximum of 210 watts can be drawn on the wire safely. If 20-gauge wire is used, a maximum of 420 watts can be drawn safely.

Incandescent calculation

Two 100 light incandescent strands will be compared. One strand has 20-gauge wiring and the other has 22-gauge wiring. The wattage for both is the same at 40.8w. The maximum amount of strings that can be connected to stay under the 210-watt limit is 5. The 20-gauge wire can have 10 strands connected to stay under the 420-watt limit.

LED Calculation

Two led mini-lights (T5-type) will be compared for this calculation. The 22-gauge wire has 60 bulbs per strand for a total of 4.5 watts per strand, which means 45 strands can be chained together to stay under the 210-watt limit. The 20-gauge wire has 50 bulbs per strand for a total of 20.4 watts per strand, which means 21 strands can be chained together to stay under the 420-watt limit.

Ignoring the wattage limits will cause excessive heat and increased risk of fire, and calculating safe chaining of lights is important if hanging a lot of Christmas lights.

Extension Cords

Extension cords come in a staggering number of options. Light/ medium / heavy-duty, extra heavy-duty – and each comes in different wire sizes, such as 16, 14, 12, 10-gauge, etc. How do you choose the right one? Luckily, you can significantly narrow down the options when using with Christmas lights. Due to the small wattage restrictions from the UL, you can safely use a light-duty waterproof 16-gauge extension cord. If you want to get a heavier-duty cord, then there is no harm in that and it can be used for other things like landscaping power tools.

The most important thing to remember if chaining together different wire gauge extension cords is to start at the outlet with the lowest gauge extension cord and attach the higher gauge extension cords to that. Without getting too technical, this has to do with current flow vs wire resistance and the resulting heat. Example: a 150-foot run of extension cord is needed, and you have 3 cords- a 16-gauge, 14 gauge, and 12-gauge. The 12-gauge should be attached to the outlet, the 14-gauge attached to the 12-gauge cord, and the 16-gauge attached to the 14-gauge.

If you want to add some control to the lighting, a mechanical plug-in timer or electronic dusk-to-dawn timer will allow you to not worry about unplugging the lights each morning and plugging them in each night. Now all that’s left to do is plug the lights into the extension cords! Stand back and admire your well-placed lights, and the fact that you didn’t resort to a yard full of inflatables.

If you’ve enjoyed this article, check out my other articles for great DIY tips, tricks, and how-tos!

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