The average adult female Border Collie weighs between 20 and 23 pounds (9-10 kg). The Border Collie Lab Mix puppies are usually between 2 months and 3 years old. They may weigh from 1 pound to 5 pounds (0.45 0.85 kg). The average weight of the Border Collie Lab Mix puppies is 4 pounds (1.6 kg).