There is not a common amount because support is dependent on the incomes of both parties and the time-share of the child/children. Other factors include if either party owns a home, is married, pays support for other children, receives support for other children, health insurance, health expenses, child care expenses, travel for visitation, etc. Because any of these factors can affect the support calculation dramatically, it is impossible to have a "common" amount. I have seen people with 5% custody get support paid to them, and I have seen people with 50% custody paying more than other who never see their children. Most courthouses have a dissomaster program available to the public either at the library or self-help center. Entering the information in the program will give you an idea of where support payments will end up.