In family law and government policy, child support or child maintenance is the ongoing obligation for a periodic payment made directly or indirectly by a non-custodial parent to a custodial parent, caregiver or guardian, or the government, for the care and support of children of a relationship or marriage that has been terminated.

When you're using an online child support calculator, you want to be sure that the program includes up-to-date, accurate formulas that are based on the way your state calculates child support. For example, some states base child support calculations on a percentage of the obligor's income. Others use what is known as "income share," which means that they take into account the number of children in the household, as well as each parent's income, before determining the amount of child support that is owed.

Because of the variation in formulas from state to state, it is recommended that, whenever possible, parents look for an online calculator that is provided directly by the state in which the order will be (or already is) issued.