How big are the German shepherds puppies at birth?

They're the same size as any puppy, which is not very big at all. If you mean "born" as in straight out of the mother's womb, they can be a few (literally just a few) pounds and can probably fit in the palm of your hand. Within the first month drinking the mother's milk, they'll get quite a bit bigger. It's within the first three years of their lives that the German Shephards will continue to grow to be a medium/large sized dog.

Source: I used to have a German Shephard. Best dog I've ever had. They're loyal, intelligent, and everything a dog should be!