Does anyone know if there is a formula for figuring the diagonal measurement of a quilt block? Say, if I make an 8" square 9-patch block, is there a formula that I can use to figure the diagonal measurement from one corner to the opposite corner? Oh, I know I could just make a block and then measure it's diagonal, but was hoping there is some easy method to figure it out on paper. I'm wanting to make a quilt with sashed blocks on point and want it to end up a certain size, but don't exactly know how big to make my blocks and sashing. Any help would be appreciated.
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The diagonal of a square is 1.414 times the length of one side. Best to round up and trim down.
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Pythagorean Theorem? A squared + B squared = C squared is the formula for a right triangle. 8 squared + 8 squared = C squared. 64 + 64 = C squared. 128 = C squared. The square root of 128 = 11.3
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Originally Posted by ghostrider
The diagonal of a square is 1.414 times the length of one side. Best to round up and trim down.
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Originally Posted by ShowMama
Does anyone know if there is a formula for figuring the diagonal measurement of a quilt block? Say, if I make an 8" square 9-patch block, is there a formula that I can use to figure the diagonal measurement from one corner to the opposite corner? Oh, I know I could just make a block and then measure it's diagonal, but was hoping there is some easy method to figure it out on paper. I'm wanting to make a quilt with sashed blocks on point and want it to end up a certain size, but don't exactly know how big to make my blocks and sashing. Any help would be appreciated.
Don't forget the seam allowances! |
the 1.414 number is used in both directions- if you have a square you need the diagonal of- times the size of the square by 1.414- if you want to figure out the size of setting triangles for said square- to make it on point you divide by 1.414 make a square that size- then cut in half diagonally for your setting triangles.
also- if you have a square- which you multiply by 1.414- that gives you the size the square will be when put on point. |
Originally Posted by lee_stitches
Originally Posted by ghostrider
The diagonal of a square is 1.414 times the length of one side. Best to round up and trim down.
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Originally Posted by lee_stitches
Pythagorean Theorem? A squared + B squared = C squared is the formula for a right triangle. 8 squared + 8 squared = C squared. 64 + 64 = C squared. 128 = C squared. The square root of 128 = 11.3
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For quick no-math measurements I measure diagonals on my cutting mat. Quick and easy, no brain strain. Don't forget to add seam allowances.
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Originally Posted by qbquilts
Originally Posted by lee_stitches
Pythagorean Theorem? A squared + B squared = C squared is the formula for a right triangle. 8 squared + 8 squared = C squared. 64 + 64 = C squared. 128 = C squared. The square root of 128 = 11.3
Diagonals are needed for setting and corner triangles and to compute that measurement, you use the finished block size plus the finished sashing width....not adding the seam allowances. Here's a chart for you to use. http://quiltville.com/onpointmath.shtml How big do you want your quilt to be? |
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