Johann was the smallest male in his litter. He weighed 8 lbs at 8 weeks old. He's now 27 inches tall and a thin 75 lbs at 1.5 yrs old. I'm guessing the weight will go up as he gets older and bulks out some. The biggest male from his litter is much shorter (more appropriately sized for a boxer
)
I agree with the previous poster who said consider an adult boxer if you want a specific size. We were planning on Johann being boxer sized....but he's kinda boxer/great dane sized. The extra size is not a big deal to us, just made me glad we bought him such a huge crate when he was a puppy.
Personally, I'd go more by personality and which dog the breeder feels would be best for your family over size at 8 weeks.