It’s best to figure out how long your string lights should be before you purchase them—after all, it’s frustrating to realize your lights aren’t long enough when you’re midway through installation. You can avoid this by taking rough measurements of the location where you want your lights. For instance, if your patio is 20 feet wide and you want the lights to zigzag across it three times, you’ll need at least 60 feet of light. In general, it’s always best to give yourself an additional 5-foot buffer if possible.