๐งฑ Construction
Curtain Calculator
Curtain fabric is measured at the flat width, and the fullness ratio decides how much of it gathers up โ twice the window width is a standard drape, while two and a half times is generous. Curtains should also extend past the window frame so they do not block the light.
How it works
Window or opening width
Window or drop height
Fullness ratio
Number of panels
Extension past each side
Hem and heading allowance
Fabric bolt width
Curtain rod length
Total fabric width needed
Width per panel
Cut length per panel
Fabric to buy
Fabric widths per panel
Rod height above the window
Frequently asked questions
How do I use the Curtain Calculator?
Fill in the fields above โ the result recalculates instantly as you type. Everything runs in your browser, so the values you enter are never collected or stored.
Is this calculator free?
Yes. It is completely free, requires no account, and works on phones, tablets and desktops.