Child Support Estimator
Get a rough estimate of monthly child support based on income-share guidelines. Enter both parents' income, number of children, and custody split.
This is a starting estimate only — actual court orders vary by state, income type, and many other factors. Always consult a family law attorney.
$500
median monthly child support order in the US
30%
of all child support goes uncollected
50
states — each has its own formula and guidelines
Understanding the child support formula
The Income Shares Model
Most states estimate what both parents together would spend on the child if they lived together, then divide that obligation proportionally based on income. The parent with less physical custody typically pays their share to the other.
Deviations from guidelines
Courts can deviate from the guideline amount for: extraordinary medical expenses, private school tuition, special needs, significant travel costs for parenting time, or if one parent has very high or very low income.
Modifying an existing order
Support orders can be modified if circumstances change significantly — job loss, income increase, change in custody, or the child moving in with the paying parent. You must file with the court; informal agreements aren't enforceable.
Estimated monthly child support — 50/50 custody, income-share model
Child support in the US is calculated by state formula — not national law — and the amounts vary significantly between states. All states use one of three models: the Income Shares model (most common, 40 states), which splits costs proportionally to both parents' incomes; the Percentage of Income model (11 states), applied only to the non-custodial parent's income; or the Melson formula (3 states), which sets a self-support reserve before calculating support.
| Children | $4k payer income | $6k payer income | $8k payer income |
|---|---|---|---|
| 1 child | $340/mo | $510/mo | $680/mo |
| 2 children | $500/mo | $750/mo | $1000/mo |
| 3 children | $580/mo | $870/mo | $1160/mo |
How is child support calculated in most US states?
Under the Income Shares model: both parents' gross incomes are combined; the state's schedule determines the total child support obligation for that income level and number of children; each parent's share is proportional to their income contribution. Additional costs (health insurance, childcare, extraordinary medical expenses) are typically added on top and split the same way. Custody time often adjusts the base calculation — more parenting time for the paying parent usually reduces the obligation.
What percentage of income goes to child support?
Under percentage-of-income states (like Wisconsin and Texas), the standard guidelines are: 1 child = 20% of net income; 2 children = 25%; 3 children = 30%; 4 children = 35%; 5+ children = 40%. Under income shares states, the percentage varies by combined income — higher-income families pay a lower percentage of income but a higher absolute dollar amount. These are guidelines; courts can deviate based on specific circumstances.
When can child support be modified?
Child support can be reviewed and modified when there is a 'substantial change in circumstances' — typically defined as a change of 15–25% in the child support amount (varies by state). Triggering events include: significant income change for either parent, change in custody arrangement, child's changed needs (medical, educational), a parent becoming incapacitated, or the paying parent's unemployment. Orders should always be modified formally through the court — informal agreements are not enforceable.
How the income-share estimate works
Formula
Payer's Income Share = Payer Income ÷ Combined Income
Guideline Obligation = based on combined income table
Payer's Share = Income Share × Guideline Obligation
Custody Adjustment = Payer's Share × (1 − Custody% ÷ 50)Combined income → guideline table obligation → payer's proportional share → custody adjustment. The formula used here approximates the most common income-share model used in 40+ US states.
This calculator does not account for state-specific tables, tax deductions, healthcare costs, childcare costs, or existing support orders — all of which courts consider. Use it to get a ballpark, not a verdict.