There's a formula for each state and what they consider. IP to 49% of ones income can be considered

It's dependent on both parents income. The support you receive isn't intended to cover all of the children's expenses, as the custodial parent should be contributing as well.

Child support is based on income earned for both parents and the terms of custody depending on weather it's sole custody, or legal and physical joint custody, or shared custody. The amounts may vary from state to state. You can go through DSS the department of social services to have child support determined, or you can go through circuit court to have it determined. In most states if not all, the forms you will need to fill out are available on line. You can access the department of social services or your local circuit court online and find the forms needed there. Keep in mind that as of October 1st 2010, DSS (Child Support Enforcement Agency) made changes to child support payments effective October 1st, 2010. This was done to reflect changes in cost of living and take into account inflation. As with any case that involves children, it is always best to consult with an attorney and get advice prior to making any decisions.