OK, this is an "area vs dimensions" question in the Textiles department.
https://permies.com/wiki/102584/pep-textiles/Sew-small-pillow-PEP-BB
- Be at least 10x10 inches
So 10 x 10 = 100 square inches
My DiL is from Punjab and apparently, their culture prizes a pillow stuffed with mustard seed for cradling a newborn's head. I have been asked to sew the "containment" for the seed, and I'll make a couple of pillow cases for over it.
I have been asked to make it 8 1/2 x 12 which equals 102 square inches.
There was a discussion at one point about how big a round pillow needed to be to meet the requirement but it was after the fact and declared to be too small.
A quick glance suggests that the pillows are generally a minimum of 10" in each direction.
If the decision is against, I am fine with it. My DiL's cousin is a sweet lady and her first child is due in a month, so she's getting this pillow whether I can use it for a BB or not!