I am 5'1" ordered small, athletic slim build, arm length perfect, length is below knees perfect, it wraps around my body as model shows so NO I do not have to order a size up. It feels soft and thick, will bewarm, cozy and just perfect for me here in the Rocky Mountains. I will wash on a gentle delicate cyclethen air fluff in the dryer before putting on my wood rack to dry naturally. I am very happy with this purchase, I think it's a beautiful gray sweater coat, exactly what I wanted before the See full review