🪟 Curtain Size Calculator
Enter your window width and desired fullness to get a recommended curtain rod length and fabric width to buy.
What this calculator does
The Curtain Size Calculator recommends a curtain rod length and the amount of fabric you need to buy, based on your window’s width and how full you want the curtains to look when closed.
How the calculation works
Rod length starts from your window’s width plus an extension on each side (commonly 3-6 inches), which lets curtains stack fully off the glass when open and makes the window look wider. Total fabric width is the rod length multiplied by a fullness factor (2x is standard, 2.5-3x looks fuller and more gathered), then divided evenly across your number of panels. A small hem allowance is added to the finished length for sewing.
This tool gives general guidance for home decorating and shopping purposes. Always check the specific fabric or ready-made panel’s actual finished dimensions before buying.