Susan asked: "Do you think it is ok to stitch a pattern meant for #22 on a #49 carpet?"
There is a formula that allows you to count the size of a complete project if you wish to chose different count of fabric to stitch. For example, another pattern from "Making Miniature Chinese Rugs and Carpets" by Carol Phillipson.
Dragon Pillar Rug
Stitch count 103 x 165 stitches and it calls for 22 count canvas
In order to figure out if you can stitch this rug on 40 or 49 count (or any other counts) you need divide 103/40(count) and 165/40 (count). It gives us:
103/40 x 165/40 = 2.6" x 4.1" - the size of a completed rug if you stitch it on 40 count.
So, my answer will be: yes, you can stitch on 40 count (I am not sure about 49) if you need that size of a rug.
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Good Luck, Susan!