Reference point for you, as Duffy may vary a bit on how much stuffing was added.
Arms: 11cm (to "wrist")
Diam Arms: 12.5cm
Legs: 12cm (to top of foot)
Diam Legs: 17cm
Slot for Tail: About 3cm below waistline, 5cm long
If you have a Build-A-Bear shop near you, the clothes there are just about the right size so you can see how they did it. I find that the BAB shirts are a tad too short, they are about 12.5 cm from neckline to hem.