This week, I did a Zoom presentation for a quilt guild in Canada (hello! Thunder Bay Quilters Guild!). We got into a little discussion about resizing blocks, and how to do the Math easily. I shared my method for doing this, and they all agreed I needed to do a blog about it! So here goes nothing ;)
I made four of the same star blocks in four different sizes. The first block is 12½” from flat side to flat side (this method works for any shape pieces/blocks, not just hexagons). The next size is reduced by 25% to make a 9½” block, then an 8½” block by reducing the original piece size by 33%, and finally a 6½” block by reducing the original cut size by 50%. These sizes are all raw edge size (or unfinished).
Here’s how the math works. You take the original cut size pieces, in this case, it's 3½” triangles. Remove the seam allowance (½” or .5) to make a 3” triangle. Multiply that number by whatever percentage you want the new block to be. If you want it to be 75% of the original size, you would do 3 x .75 = 2.25. Now add your seam allowance back in, making it 2.75. This is the new triangle size for a 9 ½” block.
The math for an 8½” block is as follows. 3½” - .5 = 3 x .66 =1.98 (round up to 2) + .5 = 2 ½”. So 2 ½” triangles will get you an 8½” block.
For a 6½” block this is the math. 3½” - .5 = 3 x .50 = 1.5 + .5 = 2”. So 2” triangles will get you a 6½” block.
You can use this method to resize all kinds of blocks in different shapes, remember to remove the seam allowance measurement before multiplying by the new percentage. Then add it back when you are done.
I hope all that made sense :)
Happy Sunday everyone,
Krista