Sizing is indicated in Mens, Oofos suggests the womens equivalent is plus 2, for example Mens 6 = Womens 8

Our most popular shoe soothes and reinvigorates your feet after a workout, so you'll be ready to do it again tomorrow. With OOfoam technology, the patented footbed design absorbs impact, cradles your arches and allows you to move naturally. Your feet will know the difference.