How much lights on a christmas tree

The Omni Calculator computes how many lights to put on Christmas trees.

How many lights should go on a Christmas tree?

This question gets asked so often during the holidays that everyone from retailers like Lowe’s to publications like Real Simple and Better Homes & Gardens have tried to answer it.

“A good rule of thumb is 100 lights for every foot-and-a-half of tree,” according to Lowe’s. But Better Homes & Gardens recommends using three 100-light sets for every foot of a tree’s height. And Real Simple suggests 100 lights for every foot.

Since there’s no consensus about just how many lights is right, trimming a tree can be daunting for novice decorators. It’s even given headaches to mathematicians like Troy Henderson, a professor at the University of Mobile’s College of Arts and Sciences in Alabama. Last year, he developed what he describes as a hack to perfectly light a Christmas tree. By thinking of a holiday evergreen as an inverted cone, Henderson used the mathematical concept known as the conical helix to determine the right number of lights for his tree. He explained:

“Our Christmas tree is 3½ feet wide at its base and 8 feet tall. When using 75 feet of lights, the vertical spacing between rotations is about 7 inches. This ensures that if we begin wrapping the lights in a conical helix pattern beginning at the bottom of the tree and vertically space the lights by about 7 inches between successive rotations, the strands of lights will terminate precisely at the top of the tree.”

Henderson has made his Christmas tree light-spacing formula available to the public, and Dominik Czernia and Álvaro Díez, physics doctoral candidates studying in Poland and Turkey, respectively, have expanded on the mathematician’s work. They feature their approach on a web tool called the Omni Calculator. The free calculator factors in tree lights and ornaments and provides users with step-by-step computation and visualization. To use it, you’ll need to know some basic information, such as your tree’s height and bottom diameter, the length and spacing of the light strands, and the diameter of the ornaments you plan to use.

So who’s most likely to use a Christmas tree calculator? Is it designed for the math-and-science crowd or for anyone who wants a perfectly decorated tree? I interviewed Czernia and Omni Calculator Project founder Mateusz Mucha about the tool.

The Omni Calculator can help you figure out how many lights your Christmas tree needs.Omni Calculator
Nadra Nittle

Who knew that decorating a Christmas tree even stumps physicists? What prompted you all to develop a web tool that could simplify this process for everyone?

Dominik Czernia

We had been wondering how many lights and ornaments make a Christmas tree so beautiful. To our surprise, it was impossible for us to make at least some rough estimations. With the help of Dr. Henderson’s formula, we developed our intuitive tool with visualization of your perfect tree with lights and baubles. The best thing about it is the simplicity — all you need to enter are your tree’s dimensions.

Nadra Nittle

The conical helix is the key to the calculator. Can you describe how this pattern works in more detail?

Dominik Czernia

We surely can all agree that when we look at the Christmas tree, its shape reminds us of a cone, a pyramid with a circular base. So what does the conical helix have in common with a cone? Imagine you’ve got a ribbon that you attach to the top of a cone. Then start wrapping it around the cone, moving downwards until you reach the base. The curve formed by the ribbon is a conical helix.

Nadra Nittle

Using the conical helix pattern, it’s helpful to look at a Christmas tree from the top while decorating it. Why is that?

Dominik Czernia

One of the aesthetic factors that please most people is uniformity. The best way to check it is to look at a Christmas tree from the top so you can see every single ornament on it. Do they look uniformly distributed from that point of view? Perfect! That’s what we’re aiming for. This is another unique feature of a conical helix; it gives us excellent uniformity.

Nadra Nittle

An efficiently decorated tree might even help cut down on electricity costs. That’s amazing.

Dominik Czernia

It surely could help. The larger number of lights naturally translates into higher power consumption. However, we don’t want to resign from the lights entirely; they’re one of those things which bring a magical Christmas atmosphere. What we can do, though, is plan in advance how bright our Christmas tree should be to buy light strands of appropriate length.

This allows us to avoid the situation in which the light strand is too long, and we hide it somewhere in the tree foliage or leave it trailing on the floor. But still, these redundant lights will use electricity and generate costs! A well-decorated tree has uniformly distributed lights around; thus, it looks as pretty as we wanted, and simultaneously, the length of strands is perfectly adjusted to the Christmas tree’s dimensions.

Nadra Nittle

Who’s the target audience for the Omni Calculator? Is it mostly math-and-science types, or have normies expressed interest?

Mateusz Mucha

Omni Calculator is used both by geeks and people who aren’t as confident with math, but it’s actually the latter group we think about the most. People have thousands of decisions to make that they should base on numbers. But they don’t think in terms of math formulas, don’t have the time, or just don’t feel like making this effort. And they end up making bad decisions. It’s our goal to make this process easy, fast, and kind of fun so that people are more likely to do the math.

Nadra Nittle

On the Omni Calculator site, there’s a funny gif of Monica from Friends. She turns a Christmas tree around to show off her expertly decorated side of the tree and to hide the very messy side her friends decorated. Do you think Monica would use your calculator?

Mateusz Mucha

Sure, but it’s actually Joey and Rachel who could get the most value out of it. Chandler suffers through Excel every day, so he’d be capable. Ross would somehow make the tree about dinosaurs, and Phoebe would try to save the tree and homeless squirrels instead.

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How Many Christmas Lights You Need to Decorate Your Home


Lee Wallender

Lee Wallender

Lee has over two decades of hands-on experience remodeling, fixing, and improving homes, and has been providing home improvement advice for over 13 years.

Learn more about The Spruce's Editorial Process

Published on 12/10/21

Fact checked by

Sarah Scott

Fact checked by Sarah Scott

Sarah Scott is a fact-checker and researcher who has worked in the custom home building industry in sales, marketing, and design.

Learn more about The Spruce's Editorial Process

ArtBoyMD / Getty Images

Christmas lights add sparkle, color, and shine to the holiday season. Yet estimating the number of Christmas lights you need to decorate your home can be difficult. House eaves, columns, peaks, windows, and other architectural features are too large to easily calculate. But there are a few rules-of-thumb and guidelines that help you buy the right number of lights to avoid blank spots or overloading the home with too many lights.

Number of Christmas Lights for Most Houses

If you want Christmas lights on your home displayed in that classic manner—on the eaves' fascia—purchase the following.

For Front Only

Use two strands of 32-foot mini lights, for a total of 200 lights, for either an average- or small-sized house.

If you prefer the larger-bulb C9 lights in 16-foot lengths, double the number of strands. So, you would use four strands of C9s, for a total of 100 lights.

The C9 strands come with a quarter to half as many bulbs as the mini lights, depending on length. Though fewer in number, C9 bulbs are far brighter than mini lights.

What Are Eaves and Fascia?

Eaves are roof projections that overhang the exterior siding. The fascia is the vertical part of the eaves that is most commonly used for attaching Christmas lights.

For Front and Two Sides

  • Average House: Use four strands of 32-foot mini lights, plus two strands of 14-foot mini lights, for a total of 500 lights. For C9 bulbs, you can use 10 of the 16-foot-long strands.
  • Small House: Use four strands of 32-foot mini lights, for a total of 400 lights. For C9 bulbs, use 7 of the 16-foot-long strands.

Large Projections

If the front or sides have large architectural details like awnings, cupolas, and gables add another 10 feet per detail.


An average-sized, newly constructed house is about 2,300 square feet. A small house is approximately half that: 1,200 square feet. For both houses, the length of the front is calculated at 50 linear feet. For the small house, each side is assumed to be 24 linear feet. For the average-sized house, each side is assumed to be 46 linear feet.

Popular Christmas Lights and Coverage

Type (Single Strand) Average Length or Area Number of Lights
Mini strand lights 14 feet 50
Mini strand lights 32 feet 100
Mini icicle lights 26 feet 300
Large C9 style bulbs 16 feet 25
Mid-size C7 style bulbs 24 feet 25
Small C3 style bulbs 18 feet 50
Net lights 4-foot by 6-foot 150
Net lights 2-foot by 8-foot 150

How to Calculate How Many Christmas Lights You Need

Calculate the number of Christmas lights needed to decorate your home by first measuring your home, then adding outdoor features.

  1. Measure the length of the front of your house (that is, the width of the house if you are looking at it from the street). Use a laser measuring tool or a tape measure.
  2. If you want to cover the left and right sides, measure those, too. The back section of homes is typically not covered, but you may decide to do this to add holiday cheer to your deck, patio, or backyard.
  3. If you want to cover the upper portion of triangle-shaped roof peaks (4:12 pitch ratio), this length will be 26 1/2 feet for each peak. This is based on a house that is 25 feet long on the side.
  4. Select the number of outdoor features desired and add them together.
  5. Add a foot or two to all of the strand (not net) light measurements. Christmas light length is expressed in two numbers: strand length and lighted length. The lighted length is always about a foot less than the strand length.

Number of Lights Needed for Outdoor Features

  • Bushes and Hedges: One to two 4-foot by 6-foot light nets per bush or hedge.
  • Trees: One 32-foot strand (100 lights) for every 1 1/2 vertical feet of an evergreen tree; or, about 500 to 600 lights for an 8-foot tree.
  • Windows: One 16-foot strand per single-width window.
  • Doors: One 16-foot strand per door.
  • Window Boxes: One 14-foot strand of 50 lights per window box.
  • Columns and Pillars: One 32-foot strand of 100 lights per 7 vertical feet of column or pillar.
  • Deck Railings: Measure the deck railing and use that measurement to determine how long the lights should be. If you plan to wrap the lights rather than use clips, you will lose about 1 foot. So, add an extra foot.


Do you want tighter light spacing? One easy way to do this is to double the lights back. Adjust the second run so that its bulbs fall between those of the first run. Just make sure that your outdoor GFCI outlet and circuit can handle the increased load.

Number of Lights for a Christmas Tree

Underestimating the number of lights on the Christmas tree results in a dark, drab tree. Too many lights overloads the tree and detracts from ornaments and the tree itself.

The easy rule of thumb is to use one strand of lights (100 lights) for each vertical foot of the Christmas tree. If you like a slightly brighter tree, you don't need much more: Just add one more strand.

Tree Height Average Number of Strands Strands for a Brighter Tree
4 feet 4 strands or 400 lights 5 strands or 500 lights
5 feet 5 strands or 500 lights 6 strands or 600 lights
6 feet 6 strands or 600 lights 7 strands or 700 lights
7 feet 7 strands or 700 lights 8 strands or 800 lights
8 feet 8 strands or 800 lights 9 strands or 900 lights

The 7 Best Outdoor Christmas Lights, Tested By the Spruce

Article Sources

The Spruce uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

  1. Characteristics of New Housing. United States Census Bureau.

  2. “Deck the Halls” Safely: CPSC Estimates More Than 15,000 Holiday Decorating Injuries During November and December. United States Consumer Product Safety Commission.

How to calculate the length of a garland for a Christmas tree using the formula and manually

Author Sofia To read 3 min Views 15.5k. Posted by Updated

British scientists were involved in decorating Christmas trees. It turns out that there is a simple formula that allows you to determine the ideal length of a garland for a Christmas tree. She was figured out by two students from the University of Sheffield in just a couple of hours.

According to their calculations, you can also accurately calculate the number of tinsel and Christmas balls. But let's dwell on the length of the garland: this is the most popular Christmas tree decoration, and also expensive. Following the advice, I got a cool lighting for an artificial Christmas tree, and now I don’t know the worries. And I won't know for a few more winters.

For calculations, you will need the exact height of the tree and the number Pi (it is 3.14).

Perfect garland formula


  • 5 m (150 cm) x 3.14 = 4 m710 cm;
  • 8 m x 3.14 = 5 m 652 cm;
  • 2 m (200 cm) x 3.14 = 6 m 280 cm;
  • 3 m (300 cm) x 3.14 = 9 m 420 cm;
  • 4 m (400 cm) x 3.14 = 12 m 560 cm.

Gets the minimum length for an existing tree. Similarly, you can calculate the length of the lights for any height of spruce. Take measurements from the lower branches, not from the floor!

If the required length of the garland does not coincide with a round number, for example 6 m 280 cm, then choose a model of 6.5 or 7 m. It is better to buy decorations a couple of meters longer than to contemplate dim lights on three branches.

By the way, according to the length of the existing lighting, you can choose a new spruce, if you prefer a real, rather than an artificial tree every year.

Length including the distance between the turns

When calculating, the width between the turns of the tape must also be taken into account. It will not be possible to name exactly your length with accuracy: 5-10 m will be enough for someone for a large spruce, and 15 will not be enough for someone. The best option is a step of 30 cm. To make the Christmas tree sparkle, choose a distance of 15-20 cm. For economical turns, we recommend placing no further than 40 cm from each other.

And now about the calculations. No mental effort is required, everything is already done for you. We find a site with a Christmas tree garland calculator and enter the desired data.

Here is an example of results for Christmas trees from 1 to 3 m high and 1 m in diameter. Data for a LED garland with 30 cm turns:

  • for a 1 m high spruce, choose a 10 m garland;
  • for a 1.5-meter spruce, 10 m is also enough;
  • for a height of 2 and 2.5 m we take 20 m;
  • a three-meter Christmas tree, buy a garland 30 m;

The type of winding does not have to be helical. For example, there is an option to decorate only the front of the tree. And the garlands themselves are of different types. For them, calculations are also made with a calculator.

Counting without formulas

If there is a long rope in the household, then use it as a template for future lighting. Just wind the rope around the tree, make a mark, and then use a centimeter tape to determine the exact length.

And don't forget to add the distance from the tree to the nearest outlet. If the spruce cannot be placed near the power source, then you will have to use an extension cord. Then you can save on the length of the garland, and hence on its cost.

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How to choose and decorate a Christmas tree

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October 30, 2020

If this year, instead of Courchevel, the New Year's extravaganza is destined to take place at your home, then we know how to help you!

We don't promise a secret flight to the Alps ;)

Instead, we will tell you how to wake up the festive mood with the help of a Christmas tree, a calculator and an online store.

In this article you will learn:

  • How to choose artificial spruce
  • How to calculate the garland and how best to hang it
  • How many toys do you need for the effect of "WOW!"
  • How to choose toys
  • How to hide the base

Current? Then let's go!

Which Christmas tree to choose

Do you want a live Christmas tree? Choose not sawn, but in a pot. Then you can give it to a nursery or plant it in the country, and they almost do not crumble. You can buy, for example, in OBI.

If minimalism (you can't hang a lot on a live spruce), Scandinavian style and retro romance are not for you, then an artificial Christmas tree will suit you better.


  • For a city apartment, a Christmas tree 180-200 cm high is enough - so that the head of the family can reach out and install a star on top.
  • For a cottage, if the ceiling allows, you can take it higher (the main thing is that at least a meter remains to the ceiling, otherwise the tree will look bulky).
  • If there is a task to save space, then look for a Christmas tree that is narrow at the bottom, similar in shape to a cypress.

Type of needles (usually indicated in the product description):

  • PVC fabric - when the needles look like a multilayer fringe. Usually such “needles” are soft and fluffy, but they can wrinkle during storage, and the Christmas tree needs to stand for a day before decorating to straighten it out. Often such Christmas trees are sold "snowy" - covered with white flock flakes.
  • Line. This, of course, is a matter of taste, but such needles look like a plumbing brush. But voluminous and inexpensive :)
  • Cast needles - when each branch is molded from plastic and strung on a wire base. A little harsh, but it looks as realistic as possible. Such Christmas trees are usually the most expensive.

Christmas tree color

Soft Christmas trees (which are like fringe/tinsel) come in different colors: white, red, silver, gold, and even pink and blue. Room for experiments!

How to calculate the length of a light garland

Christmas tree bought, next question - lights.

By the way, there are Christmas trees with built-in lighting - it's convenient (fewer wires and no need to worry about the calculation of the garland).

  • Need a wow effect? Then we take 100 light bulbs (LEDs) for every 30 cm of the height of the Christmas tree. That is, for a Christmas tree 180 cm high, you need a total of 180/30 * 100 = 600 light bulbs. In order not to wrap wires up to the very needles, we are looking for a garland with frequently planted diodes (every 3-5 cm).
  • If an angelic glow is not required, but you just want not to miscalculate with the length of the wire, then we consider this: multiply the height of the Christmas tree in cm by Pi and 2. Then for a Christmas tree 1.8 m high, you need about 12 meters of garland. IMPORTANT! Here we consider the height not from the floor, but from the lower tier of branches to the crown.

How do we hang?

Life hack: in a vertical zigzag, not in a spiral - it's easier to hang and take off. First, distribute the garland over the visible part of the Christmas tree (it is not necessary to decorate the side facing the wall;)) And then slightly deepen it to cover the wire with branches. Don't overdo it with depth! It is not worth highlighting the trunk or the central rod, which is often a bit bald.

How to hang a LED garland on a Christmas tree

How to calculate the number of toys

British scientists (who else, if not them) have deduced the formula for the ideal number of balls on a Christmas tree. And it's not a joke! Based on the laws of proportion, they got a factor of 0.21. That is, a harmonious number of balls is obtained, equal to the height of the Christmas tree in cm, multiplied by 0.21. For a Christmas tree 180 cm high, we get 31 balls. Such a Christmas tree will look like this. Pretty, but somehow not fabulous :) There is a suspicion that this formula was developed exclusively for living specimens, since they rarely withstand rich theatrical decor.

For dense decorations, the formula "Height in cm x 0.7" is more suitable - that is, about 150 toys per 180 cm Christmas tree.

Well, for those who appreciate accuracy in everything, the most confused formula. Humanitarians scroll further;)

Calculate the area that we want to cover with toys using the formula for the area of ​​the lateral surface of the cone. To do this, we multiply the length of the lower branches by the distance from the tips of the lower branches to the crown and by the number Pi.

If the Christmas tree stands against the wall, then you can decorate 2/3 that are visible. And if in the corner, then half is enough.

Next, decide how thick we want to decorate. The maximum effect is 70 toys per square meter. It's like this:

Then for a Christmas tree 180 cm high and, suppose, lower branches 65 cm, we get such a calculation.

Number of toys = P (3.14) * 1.65 m * 0.65 m * 70 pieces = 235 pieces for the whole Christmas tree.

AND 235*2/3 = 157 toys per visible part.

What toys to choose

For a live Christmas tree, some easier :)

For an artificial one - any to your taste.

Let's just give a couple of life hacks.

  • All toys can be conditionally divided into basic and thematic. The simplest Chinese balls can be basic - we fill the “holes” between the branches with them, mask the translucent trunk, etc. Thematic (or focal) can be selected on one topic. For example, "The Nutcracker", "Ballet", "Vegetables / Fruits", "Space", "Sea", etc. Toys in these photos can be bought in the online store Your Christmas Tree .

The basic rule here is: the more diverse the toys are in shape, the more interesting the decor will be. We recommend taking the base 60% and thematic 40%.