What is the standard of a healthy kitten?

The average weight of healthy cats at birth is about100g. Height10cm, width 4cm. A normal kitten weighs about140g in the first week of birth. Note that a kitten weighing less than100g may be ill or malnourished, so it needs to be taken to a veterinarian for treatment and examination. Generally, a normal kitten born 1 to 2 weeks old weighs about113-170g, which is smaller than an adult's hand.

Most 2-3-week-old kittens weigh between 170-225g. 4-5-week-old kittens weigh between 225 and 450 grams. 7-8-week-old kittens weigh between 680 and 900 grams. Three-month-old kittens will gain a pound every month in the following days until their weight is stable at around 10 pound (4.5 kg).

So, a 3-pound cat is about 3 months old and a 4-pound cat is about 4 months old. Although this is a general standard, it is still helpful to infer the age of cats around 12 weeks. Most cats will weigh 10 kg in adulthood. From this we can guess the age of the cat.