I put 38 duck eggs in the incubator on Sunday. I got a dozen khaki campbell duck eggs from ebay. Half a dozen Aylesbury and khaki campbell duck eggs in an exchange for guinea fowl eggs from iaf on the river cottage forum and 24 khaki campbell duck eggs from the rare breed sale in York. If you do your calculations then you are right to think that not all the eggs have gone into the incubator, this is because some of the eggs were broken or cracked, so I put 38 eggs into the incubator. The duck eggs take 28 days to hatch so I’ll let you know how the eggs get on.