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.

If you need to end up with a finished 2 1/2 square then before sewing it would be 3". If you wanted a 2" finished square then you would cut at 2 7/8".

The term "finished" refers to the size of the HST after it is sewn into the quilt. The term "unfinished" refers to the size of the HST (or other block) before sewing into the quilt. It sounds like you are looking for a 2 1/2" unfinished HST which will finish at 2" after sewn into your quilt. If so, you will need to start with 2 7/8" squares to make the HST.

The terms can be a bit confusing since when you finish making your block, it comes out to an "unfinished" size until you put it in a quilt which takes the 1/4" seam allowance off on all four sides.

Hope this helps.

You gave a great simple explanation!! That's it in a nutshell!!

Often new quilters confuse finished size with block size. If I'm doing a 2 1/2" square I start with 3".

Lanny

I always add a full inch to the finished size I am looking too. 2&1/2 finished, use (2) 3&1/2 inch. It's easier to trim than to come up short, even a small amount matters in accurate piecing.

if you want them to finish at 2", be 2 1/2" as individuals you add the 7/8" to the 2"- not the 2 1/2" size (you add to the finished size- which would be 2"-not 2 1/2" the 2 1/2" is the unfinished size you want.
the way you did it is correct for making 2 1/2" finished blocks...unfinished 3" --- 1/2" seam allowance

Or you could use the Strip Tube ruler and method by Cozy Quilt. If you want more information, PM me.

Nothing you did it correct and they are correct. Now when you sew those together in the quilt they will be 2 1/2 half square triangles finnished size. You just did not use them yet in the quilt top. when you piece you will loose 1/4 inch on each side. So the 3 inch will go to 2 1/2 inch.