A quick income-shares estimate of monthly child support from both parents' incomes, the number of children, and parenting time — with a link to your state's official calculator to confirm.
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Read this first. Child support is set by each state's own legally binding formula — this tool only gives a simplified ballpark to orient you. Your state's official calculator (linked with your result below) and the court are the real authority. Don't make decisions on this estimate alone.
This estimate combines both incomes, applies a simplified share of income that families typically spend on children (about 17% for one child up to roughly 31% for three or more), splits that obligation by each parent's income share, and adjusts for parenting time. Real state formulas add health insurance, childcare, tax effects, and parenting-time thresholds that this does not. Verify with your state's calculator and an attorney.
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How child support is calculated
Child support is different from asset division because the court is not trying to split a marital balance sheet. The goal is to make sure the children keep receiving financial support from both parents after the household separates. Every state has its own binding guideline, but most start from the same baseline question: how much of the parents' combined income should reasonably be available for the children each month?
Most states use an income-shares model. The state combines both parents' gross or adjusted incomes, finds the basic child-support obligation in a statutory schedule, then assigns each parent a percentage of that obligation based on income share. If Parent A earns 60% of the combined income and Parent B earns 40%, Parent A is generally responsible for 60% of the basic obligation before parenting-time and add-on adjustments. The parent with fewer overnights usually pays their share to the parent with more day-to-day expenses.
This estimator uses that logic in simplified form. It annualizes both parents' income into a monthly combined income, applies a child-cost percentage that rises with the number of children, assigns the obligation to the higher earner by income share, and then reduces the result for that parent's overnight time. In formula form for income-shares states: combined monthly income x estimated child-cost percentage x payer income share x payer noncustodial-time share = estimated monthly support.
A smaller group of states uses a percentage-of-income model. Those guidelines focus mainly on the paying parent's income and the number of children rather than both parents' combined income. The simplified formula is closer to: paying parent's monthly income x statutory child percentage = base support, with possible parenting-time and add-on adjustments. This is why two families with the same total household income can see different results depending on the state and which parent earns more.
Official worksheets are more detailed than this quick estimator. They may define income differently, cap or phase schedules at high income levels, add health-insurance premiums, allocate work-related childcare, account for other children, credit extraordinary medical costs, and change the formula when shared parenting crosses a specific overnight threshold. Some states adjust support gradually; others change the calculation only after a parent reaches a set percentage of parenting time.
Use the estimate above to understand the moving parts before you open the official worksheet. If the number looks high, test which input is driving it: combined income, number of children, payer income share, or overnights. If the number looks low, remember that health insurance, daycare, arrears, private-school costs, and unreimbursed medical expenses may sit outside the basic obligation. For the property side of your divorce, use the asset division calculator; for spouse-to-spouse support, compare the alimony estimator.
Frequently Asked Questions
How is child support calculated?
Most states use an income-shares model: combine both parents' incomes, estimate what the family would spend on the children, then divide that between the parents in proportion to income. The parent with less parenting time usually pays their share to the other. A few states use a percentage-of-income model based on the paying parent's income alone.
Why does my state's official calculator give a different number?
This tool is a simplified ballpark. Your state's official calculator uses its own legally defined schedule, income definitions, and adjustments for health insurance, childcare, other children, and parenting-time thresholds. Treat the state calculator or court worksheet as authoritative.
Does custody or parenting time change child support?
Yes. In most states the share of overnights affects the amount — more shared time generally lowers what the higher earner pays, though many states only adjust past a threshold (often 30–40% of overnights). This estimator scales by the paying parent's share of time as a rough approximation.
Is child support taxable?
No. Under federal law child support isn't deductible for the parent who pays it and isn't taxable income for the parent who receives it. That's different from alimony.