A 7ft Christmas tree typically requires around 300 to 400 feet of lights. This will depend on the style of the tree and the type of lighting you are using. The best way to determine the amount of lights you need is to measure the circumference of the tree and divide it by 3. This will give you the approximate number of lights per foot. From there, you can multiply the result by the height of the tree to get the total number of lights required.