Curtain Size Calculator
Enter your window dimensions and curtain style to get panel sizes and total fabric needed.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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Request a ToolHow to Use the Curtain Size Calculator
This calculator gives you the cut dimensions for each curtain panel and the total fabric to buy. Use it before purchasing fabric or ordering custom curtains.
- Measure your window. Measure the width of the window opening (or the curtain rod width if the rod extends beyond the window). Measure the height from where the rod will hang to where the curtains should end.
- Choose fullness. Fullness is how much wider the curtains are than the window. 2x fullness (standard) means the curtain fabric is twice the window width. This creates a gentle gather when open. 3x fullness gives a luxurious, heavily gathered look. 1.5x is a flat, modern style.
- Enter rod pocket depth. This is how much fabric is folded over at the top for the rod to pass through, plus any heading above the rod. Typically 3–4" for standard rods.
- Enter hem depth. The bottom hem is usually 3–4" deep (double fold). The calculator uses a double fold, so it adds twice the hem depth to the cut length.
About the Curtain Size Calculator
The total curtain width equals the window width multiplied by the fullness factor. This is then divided by the number of panels to get the finished width per panel. An additional 2" (1" per side) is added for side hem seam allowances to get the cut width. The cut length equals the window drop plus the rod pocket allowance plus double the hem depth plus a 0.5" top seam allowance. Total fabric is calculated assuming 54" standard drapery fabric width.
Frequently Asked Questions
How wide should curtain panels be?
Each curtain panel should be 1 to 1.5 times the window width for a flat, contemporary look. For a gathered, traditional look, each panel should be 1 to 1.5 times the window width (so two panels together give 2–3x fullness). Most interior designers recommend at least 2x total fullness for curtains that look full and substantial when closed. Panels that are too narrow look skimpy even when drawn closed.
How long should curtains be?
The most common curtain lengths are: sill length (to the window sill), apron length (4–6" below the sill), floor length (just brushing the floor), and puddle length (6–12" extra on the floor for a dramatic effect). Floor-length curtains are the most versatile and popular. Hang the rod 4–6 inches above the window frame and extend it 4–6 inches on each side of the window to make the window appear wider and let in maximum light.
What fabric width should I use for curtains?
Standard drapery fabric comes in 54" width (sometimes 60"). This calculator assumes 54" wide fabric. If each panel cut width is under 54", you need one fabric width per panel. If the panel cut width exceeds 54", you need two widths seamed together per panel. Very wide windows with multiple panels rarely require seaming because the panels are narrow enough to cut from a single fabric width.
Should I measure from the floor or the rod for curtain length?
Measure from where the bottom of the rod or ring will sit (not the top of the rod bracket) to your desired hem location — the floor, the sill, or 0.5" above the floor. If you are using ring clips, measure from the bottom of the ring since the fabric hangs below the ring. If using a rod pocket or tab top, measure from the top of the rod. The curtain length you enter in this calculator should be this rod-to-hem measurement.