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Calculating Yardage (Quilting Maths)

| 3 min read

Calculating yardage is much easier than you think. It does involve a bit of maths, but don’t worry, this step-by-step guide by Sewing Street Guest Designer, Emma Bradford, will get you calculating your own yardage in no time. These calculations are based on cutting fabric in to strips across the width first, then sub-cutting these strips into the required patches or shapes.

Deciding on Width of Fabric (WOF)

The width of most quilting cotton ranges from between 40 to 44 inches. Where the calculations call for the width of fabric in inches, you can either measure the fabric to get the exact width, or you can estimate it at 40 inches to be on the safe side. I tend to use 40 inches (101cm) as a rule as too much yardage is always better than not enough.

Calculating yardage required for squares or rectangles

If your quilt calls for a certain number of squares or rectangles, use this formula to calculate how much fabric you need to cut all of them. You must always round down your answer at this step.

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(Width of Fabric) ÷ (Width of square or rectangle) = Number of squares or rectangles produced per strip of fabric cut WOF

The formula above tells you how many patches you can cut per strip WOF.

You now need to determine how many WOF strips you need to cut to get the required number of squares or rectangles needed for your quilt. You must always round up at this step.

(Total number of patches required) ÷ (Number of squares or rectangles produced per strip WOF) = Number of strips required

Using the number of strips required, you can now calculate how much fabric you need for all your squares or rectangles.

(Number of strips required) x (Length of square or rectangle) = Length of fabric in inches required to cut all squares or rectangles

To convert the number of inches into metres, use this formula:

(Length of fabric in inches) x 2.54 = Length of fabric in cm

Example:

I have a quilt pattern that requires me to cut 108 squares that are 4½ inches square. This is how I calculate the yardage.

1) (Width of Fabric) ÷ (Width of square or rectangle) = Number of squares or rectangles produced per strip of fabric cut WOF 40 ÷ 4.5 = 8.89

This tells me, after rounding down, that I can cut 8 squares per strip WOF

2) (Total number of patches required) ÷ (Number of squares or rectangles produced per strip WOF) = Number of strips required 108 ÷ 8 = 13.5

This tells me, after rounding up, that I need 14 strips WOF

3) (Number of strips required) x (Length of square or rectangle) = Length of fabric in inches required to cut all squares or rectangles 14 x 4.5 = 63

This tells me that I need 63 inches of fabric to cut 108 squares 4½ inches square.

4) (Length of fabric in inches) x 2.54 = Length of fabric in cm. 63 x 2.54 =160.02

This tells me that I need at least 1.61 m to cut all my squares.

If the length/width of your shape is given in imperial measurements, use this table to convert the extra fraction (if any) into decimals you can use in your calculations.

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