The size of flag is dependant on the size of the flagpole. For porch mount flagpoles the 3 x 5 Ft flag is the most common. For in-ground flagpoles the general rule of thumb is that the height of the flag should be 1/5th the height of the flagpole. For example take a 25 ft high pole – 1/5th of the 25 ft leaves 5 ft. So that would carry a 5 x 8 ft flag. Please be aware of the size of flag that is recommended for your flagpole. Flying a larger flag than is recommended by the manufacturer may result in damage to the flagpole. Common size range chart 15’          3’x5’ 20’          3’x5’-     4’x6’ 25’          4’x6’ –   5’x8’ 30’          5’x8’ –   6’x10’ 35’          6’x10’ – 8’x12’ 40’          6’x10’ – 10’x15’ 45’          8’x12’ – 10’x15’ 50’          10’x15’ -12’x18’ 60’          10’x15’-                15’x25’ 70’          12’x18’ – 20’x 30’ 80’          15’x25’-                20’x38’ 90’          15’x25’ -20’x38’ 100’        15’x25’ -30’ X 60’