Here is a custom sleep sack that I raced to finish before my own baby arrives (39 weeks today). This is for a 4-month-old with room to grow. The top is 17 inches around (very stretchy). The entire length is 30 inches and the bottom edge is 19 inches across. Inside, the lining is a navy blue super-soft cashmere at the top and a plum-colored soft merino wool towards the bottom.