Half square triangle question.
 

I know this is a stupid question, but I'm dealing with a finished outline of a quilt, no directions, and my mind has drawn a blank. In the outline, the finished space for two halves of a half-square triangle is 4 1/2 inches square. I know I need to add seam allowances to that. Does that mean I am actually making a 5 inch triangle pair? It makes sense to me, but every time I think of it, I just go blank. Looking it up only gives me sizes to make a size 4 1/2 or 5 inch triangle pair. Please! I know this is a stupid question but I want to order something like Thangles to make all these half-square triangles, and I need to order the right size! Thanks in advance for any advice. :mad:

The rule of thumb is to add 7/8" to the finished size.

So to make two 4-1/2" unfinished HSTs that finish at 4" each ... you would cut two 4-7/8" squares, and sew together on the diagonal.

My preference is to add a full inch, so that I have a little extra fabric and can trim them to a perfectly squared HST. Makes for much nicer finishes to the projects.

If you plan to use thangles, you order them by the finished size of the HST. If your finished size is 4 1/2 inches, then you order 4 1/2 inch thangles. You will cut your strip of fabric 1/2" larger, which means you will cut it at 5 inches. http://www.thangles.com/howtheywork.html

There are no 'stupid' questions!!! You can ask ANYTHING here and someone will have a solution!!! It's how we all learn!!!:)

Or another way to answer your question is a FINISHED 4 1/2" square triangle is 5" before you sew it into the quilt.
You would cut 4 1/2" + 7/8" = 5 3/8" (so cut the squares at 5 1/2", make your triangle then trim down to 5").

Instead of ordering Thingles you might want to look into a CD called Triangulations. Its ~$30 but well worth it. It has HST and flying geese in every size possible that you can print out. Definitely worth the money, you just print out the size you need. It is something that you will probably use for many, many years. Good luck!

i agree too !!!! Sometimes the math just doesn't seem to add up !!

Thank you so much everyone! You have been VERY helpful, all of you, and I appreciate it. I finally "got it" from all your answers!