Measure and note the length of the curtain while it is hanging in place. Use a yardstick or tape measure to measure from the top of the curtain to the lowest portion of the hem.
Divide the height of the curtain by 1.6. This number is rounded and derived from the golden ratio, observed with frequency in nature and geometry and first described in the early 16th century.
Subtract the quotient from the height of the curtain. For example, if the curtain is 6 feet tall, divide 72 inches by 1.6. The quotient is 45 inches. Using the golden ratio, the curtain is divided into upper and lower sections by installing a hook 45 inches or 27 inches from the top or the bottom of the curtain. Decide whether you want to divide the curtain above or below its vertical center.
Measure down from the top of the curtain to the calculated height of the curtain hook. Mark the wall or window molding where you intend to install the hook. Transfer that measurement to the opposite wall or window molding so the hooks are installed at the same vertical level.