Whether you wish to mount a small flag to the front of your house or are working with a community group to erect a large flag in a public park, you won't use the same length of flagpole. Flags are available in a long list of sizes, and the size of each flag dictates the appropriate length of its flagpole.
Probable Pole Height
For small flags such as those you might mount at home, your pole should be on the shorter side. For example, a flag that measures 3 feet by 5 feet needs at least a 15-foot pole. A 20- to 25-foot pole is appropriate for a flag that is 4 feet by 6 feet. The pole size should continue to increase based on the flag size. A 50-foot pole works for a flag that measures 10 feet by 15 feet, while a 75- to 100-foot pole is necessary for a flag that is 15 feet by 25 feet.