Add up all monthly expenses you pay for and divide in half . Thats how much
I'm not generally a petty person(not saying you are) but I value my child's father a lot and I believe that what's best for my children is for him and me to be good and stable and if he is struggling (Doesn't have the kids often) I would still give him money, instead of asking for it. So basically it depends on how stable he is.
Depends on income ... I get £200 a month but he's got another child so also pays her mum £200
My daughter’s dad earns £2500 a months and pays £65 a week. CMS calculated this amount.
Do it through the courts. Get him on child support. Otherwise if he decides to stop paying, you can't get retrograde payments and have no way to make sure he actually pays.
It depends on his income.