A general formula for calculating downrod length is: ceiling height in feet minus 9′ = downrod length. This formula is based on the fan-to-floor distance of 8 feet plus 1 foot for the dimension of the fan. So if your ceiling height is 12 feet, you need a 3 foot downrod in order to properly position the fan 8 feet from the floor. Using long-length downrods for fan installations actually help stabilize fans and reduce the potential for wobble. Think of a grandfather clock pendulum and its slow, heavy swing versus a smaller clock pendulum with a fast, unsteady swing. Weight and length combine to create stability, reducing wobble, whether it is in a ceiling fan or a clock pendulum.