A Siamese kitten weighs between 4 to 8 pounds (1.8 to 3.6 kilograms) at maturity. However, the weight of a Siamese kitten can vary depending on its age, breed, and overall health. On average, a kitten may weigh around 2 to 3 pounds (0.9 to 1.4 kilograms) when it is 4 months old. It is important to note that the weight of a kitten can fluctuate as it grows and develops.