Help! I followed the directions for half square triangles ie. adding 7/8 " to end square size.
I needed to end up with 2 1/2 " square. Cut 2 squares at 3 3/8 ". Sewed and cut, ironed. Square ended up 3". What did I do wrong.

After you sew your 3 inch squares to other 3 inch squares, they will end up being 2-1/2 inch finished squares.

1/4 inch on each side "goes away/disappears" in the seam allowances.

I have to agree with bearisgray here. Umm, you will probably step back and get a huge chuckle when the light bulb turns on. Not to worry though. It happens to all of us.

You could always trim those 3" ones down to 2" unless you have another use for them.

If you want a 2" finished square, you would cut them at 2 7/8". Sewn together they will be 2 1/2" :D:D:D

What size "finished" square are you trying to make?

Since I always overcut, I cut 3" squares to get 2" finished HST. Before I go to the next step I trim them to 2 1/2". If your blocks are supposed to be 2" finished, then trim what you have to 2 1/2" and you will be fine.

Whatever you want your FINISHED size to be, add 7/8" to that measurement...example..if you want your squares to be 2" finished, cut size would be 2-7/8"...after sewing the triangles, the unit will measure 2-1/2", but after sewn into block, then it will be 2". Hope that helps.

When it is just about right sized, it's too fiddly to shave that wee bit., so I always add a full inch! ... easier to trim with that little bit more.

Needed 2 1/2 " finished square prior to sewing block pieces together.