Curtain & Drapery Fabric Calculator

Calculate the number of fabric widths, cut length per panel, and total yardage for your curtains or drapes, with fullness, pattern repeat, hem allowances, and returns all factored in correctly.

How it's calculated

First, we find the total gathered width the fabric must cover: rod width multiplied by the fullness ratio, plus the returns and overlap allowance:

required width = rod width × fullness + returns & overlap

Divide by the usable fabric width to get the number of fabric widths (panels sewn side by side):

widths = ⌈required width ÷ fabric width⌉

Each panel's cut length is the finished length plus hem and header allowance. If there's a pattern repeat, we round the cut length up to the next whole number of repeats so the design aligns across panels:

cut length = finished length + allowance
if repeat > 0: cut = ⌈cut ÷ repeat⌉ × repeat

Total fabric = widths × cut length, rounded up to the nearest ⅛ yard (or 0.1 m). Results err toward buying more fabric, never less.

Curtain fullness ratio by heading style

Fullness is the single biggest factor in how much curtain fabric you'll buy: it's how many times wider than the rod the flat fabric needs to be so the finished curtain looks gathered instead of skimpy. Match the ratio to your heading style. The calculator's heading dropdown sets these automatically, and you can override the number for anything in between.

Heading styleFullness ratioLook
Grommet / Tab top1.5×Relaxed, modern folds
Rod pocket / Pencil pleat2×Standard gathered fullness
Pinch pleat / Goblet pleat2.5×Tailored, formal drapery
Sheer / Luxe3×Soft, very full gather

Higher fullness = more fabric widths = more yardage. When in doubt, round up rather than down.

How to measure your window for curtains

Enter the rod width and finished length above; the calculator adds hem, header, returns, and overlap for you.

Curtains with a pattern repeat

Patterned and printed drapery fabric has a vertical pattern repeat, which is the distance before the design starts over. To keep the print aligned across every panel, each cut length is rounded up to a whole number of repeats, which adds fabric. Measure from one point in the design to where it appears again and enter that number; leave it at 0 for solids and non-directional textures.

Common questions

How much fabric do I need for curtains?

Multiply your rod width by the fullness ratio for your heading (1.5× for grommet, 2× for rod-pocket or pencil pleat, 2.5× for pinch pleat), add a few inches for returns and overlap, then divide by the usable fabric width to get the number of fabric widths. Each width is cut to the finished length plus hem and header allowance. Enter your window measurements above and the calculator returns the exact yardage.

What fullness ratio should I use for curtains?

Fullness depends on your heading style: grommet and tab-top panels look best at 1.5×; rod pocket and pencil pleat headings need 2×; pinch pleat and goblet pleat headings require 2.5×; sheer panels meant to look luxuriously full should be 3×. The heading-style dropdown in the calculator sets these automatically.

What are returns and overlap allowance?

Returns are the short fabric sections that travel from the end of the rod bracket back to the wall, so the curtain wraps around and blocks light at the sides. Overlap is where the two panels cross slightly in the center. Together, 6 to 10 inches (15 to 25 cm) is typical. This calculator defaults to 8 inches (20 cm), which the original prototype omitted, leaving it out underestimates yardage for pleated drapery.

What is the standard width of drapery fabric?

Most home-décor and drapery fabric is woven 54 inches (137 cm) wide, which is the default in this calculator. Some sheers and wide-width drapery fabrics run 110–118 inches so a curtain can be cut in one piece with no vertical seams. Quilting cotton, by contrast, is only 42 inches. Set the usable fabric width to match the bolt you're buying.

What is a pattern repeat and why does it matter?

A pattern repeat is the vertical distance before a printed or woven design starts over. It matters because the design has to line up across every fabric width and from panel to panel, so each cut length must be rounded up to a whole number of repeats. A large repeat can add a surprising amount of fabric, which is why the calculator factors it in.

How do I measure a vertical pattern repeat?

Find one distinct element in the design (a flower, a stripe, a diamond) and measure vertically down to where that exact element appears again. Enter 0 if your fabric is solid, has a non-directional texture, or has a horizontal-only repeat.

Why might my workroom give a different yardage number?

Workrooms may add extra for specific heading hardware, vary seam allowances, or include a cutting waste factor. This calculator gives a reliable estimate using industry-standard conventions; confirm with your workroom for large or expensive purchases.

What is hem and header allowance?

This accounts for the fabric folded over at the bottom hem (typically 4–8 inches, doubled) and the fabric used by the heading treatment at the top (a rod pocket, casing, or pleating tape). 16 inches (40 cm) is a reasonable default covering a standard hem and most heading styles.

How do I measure a window for curtains?

Measure the full width of your curtain rod or track (not the window glass) for the width, and measure from the top of the rod down to where you want the curtains to end (sill, below sill, or floor) for the finished length. Hang the rod 4–6 inches above the window and extend it 6–12 inches past each side so the open curtains clear the glass. Enter the rod width and finished length above.

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