Math problem with square in a square
 

My cousin and I are helping another cousin finish a baby quilt for her now 10 year old granddaughter. We are sashing the blocks created 10 years ago with black. I got over zealous with my seam ripper and tore the first sashing (not sure that sashing is the right word for the dotted part). So, I am replacing it. How do you measure the square and figure out what size to cut it? The charms are not exactly square, but are about 5 X 4 7/8". I'm going to need to square it up to match the others, so will need a little slop. I'm not sure if they used squares and trimmed them, or used triangles. How do I measure the size of the square to use? (I hope this makes sense.)

I went to quilters cache and found a formula to do this. They say measure your center square (5"), then divide by 1.414 (which equals 3.536). Then round up to the nearest 1/8th. (3.536 rounded up to the next 1/8th would be 3 and 5/8.) Then add 7/8. (3 5/8 + 7/8 would be 3 and 12/8, which would be 4 1/2) I cut that and the diagonal is 6 1/4. That can't be right.

What am I doing wrong?

Would it be a problem to go with that size and reduce it down to the correct size when you square it up?

bkay
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You might find it helpful to google ‘square in a square quilt block tutorial.’ There are a number of ways to achieve the block you want and some very helpful tutorials online.
I hope I have been able to help you.

making the outside triangles larger is fine. then trim leaving a good 1/4 inch past each center square "corners". some leave even more room so it "floats". just depends on the look you want. Good luck!

Here you find a calculator:
http://www.quiltersparadiseesc.com/C...Calculator.php

According to my calculations, 4.5" square cut on the diagonal is correct.
They give you a bit of wiggle room so you can trim it down after sewing
your Sq. in Sq.

I tried it with a 4" and it didn't work. Then went back to a 4.5" and it worked, thank goodness.

Thanks for your help.

bkay

Bonnie Hunter (www.quiltville.com) has a great chart on this.

If the side of your square is 5", cut a square 1" larger (6") and cut twice diagonally.

using 1.414 is correct - it's a quilter's magic number:

...if you know the side measurement of a square (or know the short side of a right triangle) and want to know the diagonal (long side of a triangle), multiply the side/short measurement by 1.414.
...if you know the length of the diagonal of a square (or long side of a right triangle) and want to know how large to cut a square so you get that size diagonal, divide the diagonal (long side) by 1.414.

As several others have said - round up and trim later. This is a great tool for square in a square, figuring setting triangles, etc.

You are making it harder on yourself than you need to (we so often do that! LOL). Measure the current dark piece and add 1/4" to 1 side (the side already sewn on). Sew it on, press, then measure the side and add 1/4" to the side sewn on. That will be the measurement for the side pieces. Yes, you can always cut them a tad bigger to square off later, but these measurements should work. Another tip for all of us who can be math challenged at times is to trace the block onto graph paper, cut the pieces out (after labeling them) and measure adding 1 /4" to all sides (except outer side if not attached to anything because that 1/4" seam allowance is still there).