[header] How to measure for curtains [title] Measure the width of each window. [step] Use a measuring tape to measure the window width-wise from one end of the window to the other. Start measuring at the outer end of the window's frame on one side and end at the outer frame on the other side. 
[title] Add 3 inches (7.6 cm) to each side for a rod above the trim mount. [step] After you measure the width of the window, add 3 inches (7.6 cm) to both sides.