# How many lights do I need for my Christmas tree?

Every Christmas tree has to have some sort of lights on it. Lights come in all kinds of varieties, from solid colors to multi-color, blinking, and so on. The list is exhaustive. When purchasing lights for your tree, it can be difficult to know just what you need, and especially what length you need!

## Fear Not!

This simple tool will help you get a good estimate of the length of lights you should plan to get. All you need is a tape measure and a few dimensions:

- The height of your tree from the bottom branch to the top
- The width of your tree from tip to tip of the bottom branches
- An idea of how many rows of lights you want

## Get Your Tree Height

Once you have these numbers ready, input them in the calculator below and get an estimate of exactly what you need.

## How Does it Work?

This is all pretty simple really, just basic right triangle geometry. The key is knowing the height of the tree and the width at the base. Once we know those two things, we can calculate the opening angle of the tree. I then use that to build rows and calculate the circumference at each row. This is most certainly a rough approximation, but it should be close enough for this purpose.

## Why did I do this?

Unfortunately, I went through the process of getting a tree and lights, without thinking about just how many I needed. Halfway through putting them on, I realized I needed at least a third more to cover the entire tree. I started to think about how to figure this out in the future and decided to build a little tool to help myself and hopefully someone else!

## Do I Plan Improvements?

Yes! I hope to make this a bit more robust in the future - including being able to change units from feet to something else, and selecting either a number of rows or the space between rows.