How to figure yardage for special shapes like Tumblers, Diamonds or Kites using QuiltSandwich

We recently had a couple of people ask about adding special shapes to the yardage calculator.  This is something we are considering.  As you can imagine, the math is fairly complex and our resident math genius needs to figure out how to best calculate the cutting instructions and show a cutting diagram that will help us cut out the shapes.

In the meantime......you CAN use QuiltSandwich to calculate fabric yardage.  The method I am going to describe is not as precise as what you will normally find with the yardage calculator, but it will get you what you need.  You might just have leftover fabric- darn! ​
This method will work if you are working with either the finished size of your shape (meaning seam allowances have not been added) or unfinished size of your piece (meaning seam allowances have been added.)

What's the secret formula????

Take the special shapes that you want to cut and figure out if the closest shape is a rectangle or a square.   Then just input the size of the square or rectangle needed into the yardage calculator along with the number that need to be cut.  That's it!  

This method will work for tumblers, 30, 45 and 60 degree diamonds, hexagons and octagons.   For the kite shape use the half square triangle shape.   

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​Let me give you a couple of examples...

Tumblers!

Most tumbler shapes are closest to a square.  My drawing is rather crude, but I think it will show you what I am talking about.  I have drawn a square on my graph paper- 12 squares x 12 squares.  Each square equals 1/2".  

Let's say that I want to cut out a 6" finished tumbler.  The 6" is the widest part of the shape.  And my tumbler shape is 6" tall.  So I need to figure yardage for a 6" finished square.   

Note:  I have seen tumblers that are more rectangular in shape.  If this is the case for the shape you want to use, just use the height and width of the tumbler as the length and width of the rectangle.  Easy peasy!

In each of the drawings below each square = 1/2".

12  1/2" squares equals 6". 

So to cut a 6" finished tumbler, I need 6" finished squares.

Diamonds!

There are 12 squares across and 6 squares down, so you will need a rectangle 6" by 3".  Make sense?

Kites!

The kite shape is a half square triangle with one of the points cut off! So use the triangle shape in the yardage calculator so that the right amount of fabric is added to accommodate a 1/4" seam allowance for triangles.

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 What about trapezoids and parallelograms and prisms and 60 degree triangles???

Oh my!

For these shapes I confess-- I need to talk to the resident QuiltSandwich math genius.  I could give you the magic numbers, but I suspect there is something easier we could do.  That's why these shapes are typically cut with a template or special ruler.  But special cutting tools don't give us the amount of fabric we need to buy!  Stay tuned... In the meantime, find the size of the square or rectangle that can hold the shape for a good yardage estimate.

How much fabric?

In summary, just count up the number of squares or rectangles you need to cut out each shape individually, put in the finished size of the square or rectangle and let QuiltSandwich tell you how much fabric is needed.  

Remember if you are working with cut sizes, just change the seam allowance to 0 and you will be good to go!

Using this method means that you will have more fabric than you need.  Why?  Because when you actually cut out the shape and the ruler is rotated 90 degrees as in the case of a tumbler, you "gain" the amount of fabric that is trimmed off the square to make one tumbler shape.  Turning the ruler allows you to use the angled cut edge for the first tumbler as the angled cut edge for the second tumbler.    The same is true for diamonds.  

Hopefully this makes sense!   If not, let me know and I will try to clarify!

Here's to joyful quilting!  Don't you just love a good hack??