These materials don't stretch like sheepskin. Order your regular shoe size; if you're a half-size, size up . Strategic Sizing Tips Half Sizes: UGG boots typically only come in whole sizes.
“Initially, they felt a bit snug straight out of the box... After a few months of wear, the lining flattened, making them a little more roomy and fitting true to size.” YouTube · Wearably Weird buying uggs size guide
may run small, so you might consider sizing up for these specific styles. These materials don't stretch like sheepskin