Curtain Fabric Calculator

How This Curtain Calculator Works

Curtain yardage is more complex than most fabric projects because of how many variables interact. Our calculator handles the math that most people get wrong by hand, especially fullness ratios and pattern repeat waste across multiple panels.

The Curtain Fabric Formula Explained

Every curtain calculation follows this structure. Understanding it helps you verify any estimate, whether from our calculator, a workroom, or a fabric store.

Step 1: Calculate Finished Width per Panel

Divide the total rod width by the number of panels (usually 2 for a pair). Multiply by your fullness ratio. For a 60-inch rod with 2 panels at 2× fullness: each panel’s finished width = (60 ÷ 2) × 2 = 60 inches per panel.

Step 2: Determine Number of Fabric Widths

Divide each panel’s finished width by the usable fabric width (subtract 1 inch for selvedge from each side). For 54-inch fabric: usable width is about 52 inches. 60 ÷ 52 = 1.15 → round up to 2 fabric widths per panel. Total fabric widths = 2 panels × 2 widths = 4.

Step 3: Calculate Cut Length

Start with the finished drop length. Add header allowance (4–10 inches depending on type) and bottom hem allowance (typically 8 inches for a double-fold hem). If you have a pattern repeat, round the cut length up to the next full repeat. For an 84-inch drop with 10-inch header and 8-inch hem: cut length = 102 inches.

Step 4: Total Yardage

Multiply the number of fabric widths by the cut length, then convert to yards. 4 widths × 102 inches = 408 inches = 11.33 yards → round to 11.5 yards.

Or skip the math entirely. Enter your window measurements in the calculator above and get the answer instantly.

What Affects How Much Curtain Fabric You Need

Fullness Ratio

Fullness is the biggest yardage driver for curtains. At 1.5× fullness, curtains look flat and tailored, which is fine for casual rooms. At 2×, they have gentle folds. At 2.5–3×, they look luxuriously gathered. Sheers typically need 2.5–3× fullness to avoid looking thin and transparent. Increasing fullness from 2× to 3× increases yardage by 50%.

Header Type

The header is the top of the curtain where it attaches to the rod. Rod pockets are simplest (add 6 inches). Pinch pleats need 10 inches of header allowance and typically require 2–2.5× fullness. Grommets need about 4 inches. Ripple fold (S-fold) tracks need 2× fullness but are the most efficient at fabric use. Learn more in our window measuring guide.

Drop Length

Sill-length curtains (~63 inches) use the least fabric. Floor-length (84 inches) is the most popular choice. Tall windows and ceilings may need 96–108 inch drops. The difference between sill-length and floor-length can be 2–4 extra yards per window.

Pattern Repeat

For curtains, pattern matching is especially important because panels hang side by side. Each panel’s cut length must be rounded up to the next full pattern repeat so the design aligns horizontally across all panels. A 12-inch repeat can add 1–3 extra yards per window. Read our pattern repeat guide.

Lining

Lining protects face fabric from sun damage, improves drape, adds privacy, and insulates. Standard cotton lining uses similar yardage to the face fabric (minus pattern repeat waste). Blackout lining is heavier but uses the same amount. Interlining (for heavy thermal curtains) also matches face fabric yardage.

Curtain Fabric Buying Tips