Child Support Estimator

Child support is a court-ordered payment from the non-custodial parent to the custodial parent to cover the child’s living, educational, and medical expenses. The calculation method varies by jurisdiction but most U.S. states use one of two models: the Income Shares Model or the Percentage of Income Model.

Income Shares Model, the most common, used in roughly 40 states: Basic Support Obligation = Combined Parental Income × Support Percentage from State Table Each Parent’s Share = Basic Support Obligation × (Parent’s Income ÷ Combined Income) Non-Custodial Payment = Non-Custodial Parent’s Share − Their Direct Payments

Percentage of Income Model, simpler, used in a minority of states: Payment = Non-Custodial Parent’s Net Income × Percentage per Child

• 1 child: 17% | 2 children: 25% | 3 children: 29% | 4 children: 31% | 5 or more: 35%

Those five figures come from New York’s Child Support Standards Act, which is the most widely copied version of this model. Other percentage states land within a few points of them.

What each variable means:

• Gross Income: all earned and unearned income: wages, self-employment, rental income, dividends.
• Net Income: gross minus mandatory deductions (taxes, health insurance, union dues).
• Parenting Time Adjustment: more overnight visits with the non-custodial parent can reduce their obligation.
• Add-ons: childcare, medical premiums, and education costs are typically split proportionally on top of the base.

Which model this calculator uses, and why the income figure matters

This calculator runs the Percentage of Income model, because it needs only one parent’s income and it is the version you can sanity-check in your head. It asks for net monthly income, and that distinction is not a technicality. Enter gross by mistake on a $6,000 salary and the estimate comes out around $1,020 instead of roughly $780, so you would be planning around a number about 30% too high.

Worked example (this calculator): Paying parent nets $4,800/month after tax, one child, standard visitation.

Base obligation = $4,800 × 17% = $816/month Standard visitation carries no reduction, so the estimate stays at $816/month, or $9,792 a year.

Move the same parent to a 50/50 schedule and the calculator halves it to $408/month, on the logic that half the child’s days are already being paid for directly.

Worked example (Income Shares, for comparison): Parent A earns $4,500/month; Parent B earns $1,500/month. Combined = $6,000. State table says $6,000 income with 1 child = $1,050 basic obligation.

Parent B’s share = $1,050 × ($1,500 ÷ $6,000) = $1,050 × 0.25 = $262.50/month

Parent B is non-custodial and pays $262.50 per month (before any add-ons). Notice how much lower that is than the percentage model would give on the same $1,500: the Income Shares approach credits the custodial parent’s own earnings, so a low-earning payor usually pays less under it. When the two models disagree this much, your state’s worksheet is the only answer that counts.

Important: This calculator provides estimates only. Always consult a family law attorney and use your state’s official worksheet for legal purposes.