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Child Support Calculator
A child support calculator gives a rough estimate of monthly child support. Enter both parents' monthly incomes and the number of children, and it estimates the total monthly amount needed for the children and each parent's share of it. Every state has its own formula, so this is an estimate only — the amount a court orders can be quite different.
The paying parent usually pays their income share to the parent the children live with.
Income shares splits a combined obligation by each parent's income share. Percentage of income charges the paying parent a percentage of their own income. Both use the same guideline percentages below; real state formulas differ — this is an estimate only.
| Combined monthly income | |
| Guideline percentage | |
| Your share | |
| Other parent's share | |
| Paying parent's monthly amount |
How it works
Child support is money one parent pays to help cover the cost of raising their children after a separation or divorce. Most states use an income-shares model: they work out how much two parents earning a given combined income would normally spend on their children, then split that amount between the parents in proportion to what each one earns. The parent the children live with most of the time usually receives the payment, and the other parent pays their share.
This calculator follows that income-shares idea with a simple guideline. It adds both parents' monthly incomes together to get the combined monthly income, then applies a guideline percentage that rises with the number of children: 17% for one child, 25% for two, 29% for three, 31% for four, and 33% for five or more. That gives the total basic obligation — the estimated monthly amount for the children. Each parent's share is then their fraction of the combined income times that total.
The formulas are:
Basic obligation = Combined income × guideline %
Your share = Basic obligation × (Your income ÷ Combined income)
The other common model is percentage of income: instead of working out a combined obligation, it charges the paying parent a percentage of their own income — the same guideline percentages (17% for one child, 25% for two, 29% for three, 31% for four, 33% for five or more). Switch the model above to compare the two: the paying parent's monthly amount comes out the same either way, because their income share of a combined obligation equals the same percentage of their own income — what changes is the total obligation shown. Neither model is any particular state's formula: states set their own percentages, caps, and adjustments, and no state-specific figures are used here.
Please treat this as a planning estimate only. Every state has its own formula, and real orders take account of things this calculator does not: how many nights the children spend with each parent, health insurance and childcare costs, other children either parent supports, and either parent's other income. Some states use a percentage-of-income model instead of income shares, and some set a minimum payment. A court can also order a different amount if the guideline result would be unfair in a particular case. For a figure you can rely on, use your state's official calculator or speak to a family lawyer.
Worked example
Two parents have a combined monthly income of $8,000 and one child. What does this estimator say?
For one child the guideline percentage in this calculator is 17%. The basic obligation is $8,000 × 0.17 = $1,360 a month. That is the estimated total monthly amount for the child.
If the parents earn $5,000 and $3,000 a month, their shares split in the same ratio as their incomes. The first parent's share is $1,360 × ($5,000 ÷ $8,000) = $850 a month, and the other parent's share is $1,360 × ($3,000 ÷ $8,000) = $510 a month. In practice, the parent who pays would usually pay their share to the parent the child lives with — but remember, a real court order in your state could be higher or lower than this estimate.
FAQ
How is child support usually calculated?
Most states use an income-shares model: they estimate what parents with a given combined income would spend on their children, then split that amount between the parents in proportion to each parent's income.
Why does every state have a different formula?
Family law is set state by state, so each state writes its own guidelines, percentages, and rules for costs such as childcare and health insurance. That is why an estimate from one state can be very different from another.
Does the number of children change the amount?
Yes. The guideline percentage rises with each child, but not in a straight line: two children cost more than one, but not twice as much, because some costs are shared.
Does this calculator give the exact amount a court will order?
No. This is an estimate only. A court looks at custody time, childcare and insurance costs, other children, and state rules that this calculator does not include.
What if one parent earns much more than the other?
The higher-earning parent pays the larger share, because shares are split in proportion to income. If one parent earns all of the combined income, their share is the whole basic obligation.
What is the difference between income-shares and percentage-of-income?
Income shares works out a combined obligation from both parents’ incomes and splits it by each parent’s income share. Percentage of income charges the paying parent a percentage of their own income, with no combined total. Both use the same guideline percentages here, so the paying parent’s amount is the same under either model — only the total shown differs.