28 count is usually stitched over two squares.
14 count is stitched over one square.
This is not scary math...14 count is just 14 x 2.
Any thing over 18 count is stitched over two threads.
When I first started stitching, I knew the higher thread counts look so much like art (the holes are very tiny), I thought that a stitcher would like to see itty bitty stitches, so I designed a "Wizard of Oz" apron for my mom, who is a Dorothy. It was so perfect in a 40 count OVER ONE that mom thought I had ordered it from a printer! When I told mom that I designed and stitched it, she burst into happy tears!

I didn't even know that 40 count stitch fabric existed. Your project sounds lovely and unique. Have you considered selling your finished projects?

I have a question regarding the effect on the finished size when a 28 count fabric is converted to 14 count or vice versa. Does the conversion change the finished size of the project?

You mentioned that you used 40 count over 1. What is the end result in size and appearance? Did that change the oversize of your project? What kind of fabric did you use?

Thanks, I look forward to hearing from you again. Susie Brewer email address is susiebswi@comcast.net if you would prefer to contact me via email.

Su, I disagree with your comment that anything over 18 ct is stitched over 2 threads. HAED charts call for stitching over 1 square on 25 ct : I am preparing to start one of their designs stitching over 1 square on 22 ct to enlarge the finished product. ( unless I'm missing something😬)