What is a girls shoe size 6 equal to in women's sizes?

The general rule of thumb is that a girl's size 3 is equivalent to a woman's size 5, so I would assume that a girl's size 6 would be a woman's size 8, or improperly labeled as a woman's size 6. It also depends on where you go like a 6 in a Nike store is still kids it usually goes up to 6.5 or 7 possibly just 5.5.