The stitch count of the design is what matters, & it always stays the same. That's the number of stitches in the design height and width. The finished size of the piece depends on the fabric. If you want to use 11-ct Aida, divide the height count and width count by 11. This gives you the finished size of your design in inches & tells you how much cloth to buy. (Example: 111 x 222 stitch count divided by 11 = 10" x 20" picture to mount & frame.

For strands, I suggest test squares, starting with 4-strand floss cross stitches.

I advise you to buy Charles craft aida cloth. It is the best. I use it all the time

I downloaded a free app called XStitch Caculator. I bet there would be other apps out there.
With this one, you enter the stitch pattern height X width, the fabric count, stitching over 2?, how many inches to leave as a border, then calculate. So easy.

Thanks, All! I appreciate the help!