Formula for HSTs
 

I need to cut fabrics so that 4 HSTs sewn together will become an 8 1/2" unfinished block
I've been experimenting and all are winding up as blocks in wrong sizes.
Am hopeful someone can help me.

If I'm not mistaken, add 7/8 in. to your block size. I always add an inch and then trim down. HTH.

You want an 8 1/2" block composed of 4 HSTs? If I read it correctly, you need each HST to be 4 1/2". Cut your squares 5 1/2 inches, put two together, draw a diagonal line and sew 1/4 on either side. Cut on the line. Press and trim the HST to 4 1/2". When you take away 1/2 for the seam there's your 8 1/2".

You can add 1/2" and cut the squares 5", but it takes very exact sewing. The previous poster was right - usually a pattern will say add 7/8", but 1" is easier to measure and either way you have to trim so I prefer to use 1".

Ummm...no, you want the block to be 8" FINISHED, right? That makes each square 4" finished. So add 7/8 inch to the FINISHED size you want--cut your squares 4 7/8" (or 5" and trim), draw a line diagonally and stitch 1/4" on either side of it.

I always check each square to make sure it is the size I want (in this case, 4 1/2" before sewing them into a block too.

They are right add 1" .

This is helpful information, I will definately save for the future.

gollytwo, try it both ways and let us know. You need that HST 4 1/2" before it is sewn into your block, so cutting 4 7/8" gives you a very skimpy amount to work with and less than a 1/4" seam which would weaken a bias seam. When I wanted 6 1/2" blocks, I cut 7 1/2 " squares and didn't have much too trim.

I just did HST the patten said 2 7/8" squares and sewn and cut they measure 2 1/2". Trust me Im not perfect but they all turned out!! my block has 64 pieces so trimming down is not appealing for this project.

http://quilting.about.com/od/quiltbl...el_quilt_2.htm

This pinwheel uses 4 7/8" squares. If I were doing this method I would probably use 5" squares and then square the hst to 4 1/2".