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A large sofa: 10 to 14 yards of 60-inch-wide fabric or 16 to 20 yards of 45-inch-wide fabric. A small sofa: 6 to 8 yards of 60-inch-wide fabric or 10 to 12 yards of 45-inch-wide fabric. A small table: 5 to 6 yards of 60-inch-wide fabric or 6 to 8 yards of 45-inch-wide fabric. A standard-size armchair: 4 to 6 yards of 60-inch-wide fabric or 8 to 10 yards of 45-inch-wide fabric.
Measured width 210cm. x 2 for fullness = 420cm. divided by fabric width (137cm) = 3.07. You will then need to round this figure to the exact number it is closest to. In this example the figure is just over 3 so you would use 3 widths of fabric (one and a half in each curtain for a pair of curtains).If the figure was just below (eg 2.85) you would go up to 3.inally, multiply the length of fabric for each width by the number of widths you need to get the total amount of fabric you need. In our example this would be 195cm x 3 = 585cm or 5.85m of fabric needed.