100 Lights Per Foot is the Standard
Most people purchase 100 lights for each foot of height; this is the standard amount of lights for a Christmas tree. For example, if you have a 6 foot tall tree, you need about 600 lights for your tree.
Use More Lights for More Glow
If you want a more "sparkly" or brighter Christmas tree, buy at least 150 lights per foot or as many as 300. Another factor to consider: if your tree is wider than average, plan on using more lights per foot of vertical height; if your tree is thinner, you'll need fewer lights per foot.
Video of the Day
Determine how many lights you'll need per foot of height by how bright and twinkling you want your tree: for a subdued glow, use 100 per foot; for a more stunning effect, use as many as 300 per foot.