For custom drapery, here are commonly used formulas with examples for calculating fullness and yardage.
Formulas
Fullness = (#Cut x Fabric Width) / Overall Width
Number of Cuts = Overall Width x Fullness = _ / Fabric Width = Number of Cuts (round up to whole number)
Cut Length Including Repeat
- Finished Length + Cutting Allowance = Cut Length of Solid Fabric
- Cut Length of Solid Fabric / Length of Repeat = A (round up to whole number)
- A x Length of Repeat = Cut Length Including Repeat
- Equivalent Number 48” Cuts: (Number of Cuts x Fabric Width) / 48” = Number of Cuts Invoiced (round up to even number)
Yardage = [Number of Cuts x Cut Length (allow for repeat)] / 36
Ruffling
- (Size of Ruffle +1 x 2) = Cut Length of Ruffle
- (Coverage Area for Ruffle x 3) / Width of Fabric = # Cuts for Ruffle (round up to whole number)
- Cuts for Ruffle x Cut Length of Ruffle) / 36 = Yardage
- Swag Width (Standard) = [Board Width / (# Swags + 1)] x 2
Circumference = Diameter x pi (3.146)
To find the circumference of table cloth for fringe yardage:
- Take (diameter x 3.146) divided by 36 (round up) (this gives you the amount of yardage needed for fringe)
Examples
Examples for 1 Pair Drapes (125” Wide x 90” Long (24” Repeat, 48” Wide Fabric), Lined, 250% Full, 6” Returns Right & Left)
Cut Length (solid fabric)
90″ (finished length) + 16″ (allowance for hem & header) = 106″ (cut length)
Cut Length (if fabric has repeat)
106 / 24 = 4.41 (cut length / repeat)
4.41 = 5 (round up your answer)
5 x 24 = 120″ (round up answer x repeat = new cut length)
Overall Width
125″ (rod width) + 4″ (constant 4″ overlap) + 12″ (left return & right return (6 + 6 = 12)) = 141″ (overall width)
250% Full is 2.5 x Overall Width: 2.5 x 141 = 352 1/2 = Tabled Width
Fullness
352 1/2 / 48″ = 7.34 (tabled width / width of fabric = number of widths needed)
8 x 120″ = 960″ (number rounded up or down for exact number of widths needed x cut length – A)
960″ / 36″ = 26.67 yards (A / 36″ per yard = 27 yards needed)