How the Christmas tree lights calculator works
Enter the height of your tree, its shape and how bright you want it, and the calculator tells you how many lights you need and the easiest way to buy them as strands. It also shows how many outlets you will use. Measure the tree without the topper.
The calculation follows the most common decorating rule: about 100 lights for every foot of tree height. Slim trees need less, wide or full trees need more, and anyone who wants a glittering tree can go up to 150 or 200 lights per foot.
How many lights per foot of tree?
| Look | Lights per foot | 6 ft tree | 7.5 ft tree | 9 ft tree |
|---|---|---|---|---|
| Light and airy | 50 | 300 | 375 | 450 |
| Classic | 100 | 600 | 750 | 900 |
| Full | 150 | 900 | 1,125 | 1,350 |
| Dazzling | 200 | 1,200 | 1,500 | 1,800 |
These figures are for a standard tree. The calculator reduces the total by about 20% for a slim or pencil tree, and increases it by about 20% for a full, wide tree.
Choosing the right strand size
Lights are sold in strands of 50, 100, 150, 200, 300 and more. Fewer, longer strands mean fewer plugs and less to untangle. Strands that are too long for the tree are hard to hide. The calculator lists the combinations that get closest to your number without leaving a lot of spare bulbs.
- LED lights use little power, stay cool and can usually be connected end to end in long runs. Check the label for the maximum number of sets.
- Incandescent lights produce a warm glow but use more power. Most sets should not be joined more than three end to end, so a big tree needs more than one outlet or a power strip.
- Warm white gives a traditional look, and cool white looks modern. Do not mix the two on one tree.
How to put lights on a Christmas tree
- Plug in every strand before you start, and replace any with dead sections.
- Start at the plug end, at the bottom and close to the trunk, so the cord stays hidden.
- Work upward in a spiral. Weave the lights in and out of the branches instead of wrapping them over the surface, so they glow from inside the tree as well.
- Lay each strand along the branch, from the trunk to the tip and back, for even coverage on a full tree.
- Join the next strand where the last one ends, and keep the plugs close to the trunk.
- Step back every few feet and check for bare patches. Do this with the room lights off.
Worked examples
A 7.5 ft standard tree
At the classic 100 lights per foot, the tree needs about 750 lights. The best buy is five 150-light strands, which comes to exactly 750 with nothing spare.
A 6 ft slim tree
6 ft × 100 lights × 0.8 for the slimmer shape makes about 480 lights. Five 100-light strands, or three 150-light strands plus one 50-light strand, would cover it.
A full 9 ft tree
For a full, wide tree at classic density, 9 ft × 100 × 1.2 comes to about 1,080 lights. Six 200-light strands would give you 1,200, enough for a fuller look.
Common mistakes with tree lights
- Buying too few. If you are between two sizes, buy the extra strand. Bare patches are much more noticeable than a dense tree.
- Connecting too many sets. Overloading a strand is a fire risk. Read the label for the maximum number of connected sets.
- Not testing first. Check every strand is working before it goes on the tree.
- Mixing colour temperatures. Warm white and cool white lights look odd side by side.
- Leaving lights on all night. Use a timer, and turn the lights off when you go to bed or leave the house.
Tips for a better-lit tree
- Use indoor-rated lights only on an indoor tree, and check for the safety mark on the box.
- Put a timer on the plug so the tree switches on at dusk and off at bedtime.
- Add the lights before the ornaments and garlands.
- For a 7 ft tree or taller, string it in sections, one per strand, so one broken strand does not darken the whole tree.
- Take the lights off carefully after Christmas and wrap them around a piece of cardboard to avoid tangles.
