Guest Author - Iris ten Holder
Often it is useful to be able to determine the square footage of a round or oval rug and the quantity of material needed. This can help in preparing adequate fabric strips for the total project.
By creating a table, this information is readily available. With such a reference, it is a easier to start a new rug. This is something you can do now and keep handy for future use.
This is a two-step process. You will need to calculate the length of the braid needed for one square foot, and then you will need to calculate the square footage of the rug.
1. Calculate the length of the braid and the fabric needed for one square foot.
Assuming that the spacing is one inch, the calculation is
12 x 12 = 144
To allow for braiding (three strands (*3) plus shrinkage (*2):
144*3*2 = 864 inches
To convert to yards, divide by 36:
864/ 36 = 24 yards (one inch wide)
Thus: 24 yards per square foot
2. Next calculate the square footage of the round or oval rug.
The calculation for a circle is noted below
In spite of its irregular shape, it can easily be converted to regular shapes that are easy to calculate. To do this divide the oval into regular shapes; that is, a rectangle and two half circles, so we can use the formulas for the area of a rectangle and the area of a circle
Example: a 5 x 7 rug,
the area of the two half circles is 5 x 5, and
the area of the rectangle is 5 x 2.
For the area of the circle, take half the width (in this case 5/2 = 2.5 and use the formula below.
For the area of the rectangle, multiply length by width.
1. Area of a circle =
- a. radius squared: 2.5 * 2.5 = 6.25
- b. result multiplied by pi :6.25 * 3.14 (pi) = 19.63
2. Area of rectangle =
length x width: 5 * 2 = 10
Total area: 19.63 + 10 = 29.63
The square footage of this oval rug is 29.63 square feet.
3. Multiply 29.63 by 24. This is 711.12 yards.
Repeat this process for other rug sizes.
When starting to make the rug, make a sample first to verify the accuracy of the assumptions.
Enjoy the math!