The number of lights needed for a 6-foot Christmas tree can vary depending on several factors, including the type and size of the lights, the spacing between them, and the style of the tree. Generally speaking, it's a good idea to use at least 250 to 500 lights to ensure a nice, even glow, but this can vary based on personal preference and the look you're going for. It's always best to experiment and see what looks best for your particular tree.