Curtain Fabric Calculator

When to Use This Tool

Your window is 3 meters wide, you want center-draw curtains with a 1.8x fullness ratio, and your fabric roll is 1.5 meters wide—how many meters of fabric should you buy? With our calculator, just plug in the numbers and get instant results. Whether you're a homeowner remodeling, an interior designer, or a DIY mom prepping your own fabric, this tool saves you from doing the math manually.

How It Works & Formulas

There is only one core formula: Total Fabric Length = (Window Width × Fullness Ratio) ÷ Fabric Width × 2 (for center-draw curtains), then rounded up to the nearest meter or half-meter. The fullness ratio is typically 1.5 to 2.5; a higher ratio means denser, richer pleats. Standard fabric widths are usually 1.4m or 1.5m (narrow) and 2.8m (wide). If your window is very wide, you may need to seam fabric cuts together. The calculator automatically accounts for the number of cuts and the length of each.

For example: A 3-meter wide window, 1.8x fullness ratio, 1.5-meter fabric width, making center-draw curtains.
① Single panel coverage width = 3 ÷ 2 = 1.5 meters (each side covers half the window).
② Single panel actual fabric width = 1.5 × 1.8 = 2.7 meters.
③ Number of fabric cuts per side: 2.7 ÷ 1.5 = 1.8, rounded up to 2 cuts (seamed together). Length of each cut = Window height + top/bottom hems (usually 20–30 cm). If the height is 2.7 meters, each cut is 2.9 meters. One side requires 2 cuts × 2.9 meters = 5.8 meters. Total fabric: 5.8 × 2 = 11.6 meters, rounded up to 12 meters. Our calculator directly displays these intermediate numbers and the final recommended purchase length.

How to Use This Tool

Enter the actual width of your window in the "Window Width (m)" field, e.g., 3.
Enter the actual height of your window in the "Window Height (m)" field, e.g., 2.7.
Select or type 1.8 in the "Fullness Ratio" field (1.8–2.0 is generally recommended).
Enter the actual width of your fabric roll in the "Fabric Width (m)" field. Common widths are 1.5 or 2.8; enter 1.5 here.
Select "Center Draw (Split)", which defaults to "Yes" (two panels opening from the middle). If you want a one-way draw (a single continuous panel), select "No".
Click the "Calculate" button. The results area on the right will display the "Recommended Total Purchase Length", "Number of Cuts per Panel", "Seaming Instructions", and more.

Complete Example / Walkthrough

Primary Example: A window 3m wide and 2.7m high, using a 1.8x fullness ratio, 1.5m fabric width, center draw.

Action: Enter 3 for "Window Width", 2.7 for "Window Height", 1.8 for "Fullness Ratio", 1.5 for "Fabric Width", and select "Yes" for Center Draw. Click Calculate. The results will show:

Fabric width per panel (when split) = 1.5m × 1.8 = 2.7m.
Number of cuts needed per panel = 2.7 ÷ 1.5 = 1.8 → rounded up to 2 cuts.
Length of each cut = 2.7m (height) + 0.2m (top/bottom hem allowance) = 2.9m.
Total fabric per panel = 2 cuts × 2.9m = 5.8m.
Total for both panels = 5.8 × 2 = 11.6m → Recommended purchase 12 meters (rounded to a whole number).
Seaming instructions: Each curtain panel requires sewing 2 cuts of fabric together vertically, requiring a seam allowance. The calculator will prompt "Each cut is 1.5m wide, 4 cuts in total."

Comparison Example: The same window, using wide fabric (2.8m width), 1.8x fullness ratio, center draw.
Action: Change fabric width to 2.8. Result: Number of cuts needed per panel = 2.7 ÷ 2.8 = 0.96 → rounded up to 1 cut. Each panel only needs 1 cut, length = 2.9m, total fabric = 2.9 × 2 = 5.8m, recommended purchase 6 meters. This saves half the fabric length compared to narrow fabric, but you must confirm if the fabric pattern is suitable for wide-width orientation.

How to Interpret the Results

Recommended Total Purchase Length: The total meters of fabric you should ask for at the fabric store. It already includes hem and seam allowances.
Number of Cuts per Panel: How many pieces of fabric