Could anyone tell me how much weight kittens should gain per day. My babies are 2 days old. The biggest gain in 2 days is my grey boy who now weighs in at 6 1/2oz ( born at 4oz ) My little black girl has only gained 1/2 oz she is now 4 oz ( born at 3 1/2 oz) I think the 2 boys in the litter are greedy little pigs!! the 3 girlies must be getting less, the boys latch on like leeches ( well we are talking boobies and boys here!!) but the girls aren't as good and it takes them a while to get it sussed.