Every state sets child support with a written guideline, but the formula differs: some apply a percentage to the paying parent's income, while others combine both parents' incomes under an “income shares” model. Choose your state to see how its guideline works — the percentages, income brackets, and any cap — and to run the figure you enter through that formula. Whatever the guideline produces, a judge can order a different amount, so the state's official calculator is the authoritative tool for your case.
States use one of two main guideline models. In a percentage-of-income model, the court applies a set percentage to the paying parent's income — Texas, for example, uses 20% of monthly net resources for one child, rising with the number of children, while Nevada applies a tiered percentage to gross monthly income. In an income-shares model, used by Arizona and New Mexico, the court combines both parents' incomes, finds the total support figure on a state schedule, and divides it between the parents in proportion to what each earns. Either way the guideline is the starting point a court presumes is correct, and it is adjusted for things like parenting time, health insurance, and childcare.
The figure a guideline runs on matters. Texas applies its percentages to “net resources” — income after taxes, Social Security, union dues, and the child's health-insurance premium — and only up to a cap on monthly net resources that the Attorney General adjusts for inflation; above that cap, a court can order more based on the child's proven needs. Nevada instead uses gross monthly income and, since 2020, has had no income cap at all. Income-shares states look at both parents' gross incomes together. Because these definitions differ, a number from one state's formula doesn't carry over to another, and the official calculator is built to apply the right definition for your state.
A guideline figure is what a court presumes is appropriate — not a fixed amount. Judges can order more or less when the standard amount would be unjust or inappropriate, weighing factors like a child's special needs, a parent's other children, travel costs for visitation, and shared-custody arrangements; states also provide a low-income schedule when a paying parent's circumstances limit their ability to pay. That's why this page shows the guideline calculation on the figure you enter rather than predicting what a judge will order. For an exact number for your situation, run your state's official calculator and, when the stakes are high, talk to a family-law attorney.
Disclaimer: NotALawyer.com provides general legal information, not legal advice, and is not a law firm. Using a tool does not create an attorney–client relationship. Laws change and vary by situation — verify anything important with the official source or a licensed attorney in your state.