A - Hip Width
B - Seat Width

A - Linear Distance - While sitting on a staircase between two books, press them tightly against your hips (Greater Trochanters). While holding the books in place and without moving them, stand up. Make sure the books are parallel to each other and measure the distance between them. Remove the books and repeat the measurement to make sure you get a consistent answer.

B - Linear Distance - While sitting on a staircase, slide two books under your hips at the position that feels like the sharpest and lowest point of the bone (Ishial Tuberosities). While holding the books in place and without moving them, stand up. Make sure the books are parallel to each other and measure the distance between them. Remove the books and repeat the measurement to make sure you get a consistent answer.