You just never know how big your pup will get. Hopefully, you were able to see the parents and get their weights and can speak to your breeder to get more insight...technically, according to standard, a BT should never be over 25 lbs. But, given that so many of us have BT's from various sources - reputable, rescues and not so reputable, there are going to be discrepancies, and lets face it genetics is a lottery - you don't know what you are going to get. We thought with Rupert's parents that he would be around 20 lbs. However, he is now 10 months old and is only 14 lbs. He was actually one of the bigger puppies in the litter, so go figure. The "runt" of the litter is just about 19 lbs. Usually the weight doubles from what it was at 4 months and although not a 100% certainty, if a dog is 14 lbs. at 4 months, they will be 28 lbs. or very close to that when fully grown.