Curtain Panel Calculator
Curtains need extra width for fullness, not just to match the rod — and length has to include the heading and hem.
Why fullness matters more than rod width
Cutting panels to exactly match the rod width produces flat, stretched-looking curtains once hung. The fullness ratio is what creates the soft, draped folds — a 2:1 ratio means the total fabric across all panels is twice the rod width, gathered or pleated back to fit.
Piecing panels from standard-width fabric
If the calculated cut width per panel is wider than your fabric's width, you'll need to seam multiple fabric widths together to make up each panel — the same idea as piecing a quilt backing from narrower yardage.
Don't forget pattern repeat
Printed fabric with a repeating design needs extra yardage beyond the plain math here so the pattern can be matched across seams and across panels. Check the fabric's repeat measurement and buy accordingly if you're using a print rather than a solid.