How much child support will you pay or receive? Estimate monthly child support with this free calculator based on the income shares model used by most states — combined parental income, number of children, overnight parenting time, and add-on expenses like health insurance and childcare.
The income shares model is used by most states: both parents' incomes are combined, a basic obligation is set from marginal bands, and each parent pays their proportionate share. The overnight adjustment applies only in One Parent Primary mode.
The percentage-of-income model applies a flat guideline percentage to the noncustodial parent's income: 20% for 1 child, 25% for 2, 29% for 3, 31% for 4, 34% for 5, and 35% for 6 or more. Used by guideline states such as Texas, Illinois, and Pennsylvania (with local variations). No add-on split is applied in this mode.
Inputs: Parent A earns $4,000/mo, Parent B earns $2,000/mo, 2 children, Parent A is noncustodial with 60 overnights, no add-ons.
Calculation: Combined income = $6,000.00. Basic obligation = 15% × $2,000 ($300.00) + 12% × $2,000 ($240.00) + 10% × $2,000 ($200.00) = $740.00. Parent A's share = ($4,000 ÷ $6,000) × $740.00 = $493.33. 60 overnights < 90 → no adjustment.
Inputs: Same as Example 1, plus health insurance $200/mo and childcare $400/mo paid by Parent A.
Calculation: Add-ons = $600.00. Parent A's income share = 2/3 → Parent A adds $400.00. Total = $493.33 + $400.00.
Inputs: Parent A earns $6,000/mo, Parent B earns $3,000/mo, 1 child, 50/50 custody.
Calculation: Combined income = $9,000.00. Basic obligation = $300.00 + $240.00 + $400.00 + $80.00 = $1,020.00. Share A = ($6,000 ÷ $9,000) × $1,020.00 = $680.00; Share B = $340.00. Higher earner pays the difference: $680.00 − $340.00.
Inputs: Noncustodial parent earns $5,000/mo, 2 children.
Calculation: 2 children → 25% guideline. Monthly support = $5,000.00 × 25%.
Inputs: Noncustodial parent earns $5,000/mo, 3 children.
Calculation: 3 children → 29% guideline. Monthly support = $5,000.00 × 29%.
Note: These examples use the simplified schedules above. Actual state guidelines vary — use your state's official worksheet for a binding figure.
Overnight tiers (primary custody): 0–89 → no adjustment · 90–139 → −10% · 140–181 → −15% · 182+ → −20%
Percentage guidelines (Mode B): 1 child 20% · 2 children 25% · 3 children 29% · 4 children 31% · 5 children 34% · 6+ children 35%
Add-on costs: health insurance + childcare, split by each parent's share of combined income
Pick Income Shares if your state uses the shared-obligation model (most states do), or Percentage of Income for flat-percentage guideline states. Enter both parents' monthly gross incomes — before taxes or deductions.
Choose One Parent Primary and enter the noncustodial parent's overnights to apply the 90/140/182 tiers, or choose Shared 50/50 to compare shares directly. Add monthly health insurance and childcare costs if they apply.
The results show combined income, the basic obligation, each parent's share, and the payer's final monthly amount. The step-by-step breakdown traces every computation so you can verify it against your state's worksheet.
The calculator follows the income shares model used by most states. Both parents' gross monthly incomes are combined, and a basic support obligation is derived from the combined total using marginal bands — 15% of the first $2,000, 12% of the next $2,000, 10% of the next $4,000, 8% of the next $7,000, and 6% of anything above $15,000.
Each parent then owes their proportionate share of that obligation. In one-parent-primary custody, the noncustodial parent pays their share, reduced by up to 20% when they host 90 or more overnights a year. In shared 50/50 custody, the higher earner pays the difference between the two shares. Health insurance and childcare add-ons are split by income share and added to the payer's total.
Use both parents' monthly gross income before taxes and deductions — guidelines are calculated on gross pay.
The first $2,000 of combined income is charged at 15%, with lower rates above it — higher combined incomes owe proportionally less.
Count actual overnights per year; the calculator rounds to whole nights and applies tiers at 90, 140, and 182.
Health insurance and childcare are divided by each parent's share of combined income and added to the payment.
Both parents' incomes drive the result. The basic obligation grows with combined income, and each parent's share is proportional to their own income — so the higher earner always carries the larger share, and in 50/50 custody pays the difference between the two shares.
Parenting time matters too. In primary-custody arrangements, 90 or more overnights a year with the noncustodial parent reduces their payment by 10–20%, reflecting the everyday costs they already cover. In percentage-of-income states, the number of children sets the rate: 20% for one child up to 35% for six or more.
A raise for either parent changes combined income and both shares — child support is recalculated from the totals.
More overnights mean the noncustodial parent covers more daily costs, so their payment shrinks at each tier.
In percentage mode the rate rises with each child, from 20% for one to 35% for six or more.
Insurance and childcare can add hundreds per month — always enter them when the payer covers them.
Keep records. Pay stubs, tax returns, and proof of insurance and childcare costs make it easy to verify the numbers and support a modification later. Recalculate whenever income or parenting time changes materially.
Understand your state's model. Most states use income shares; a handful (Texas, Illinois, and Pennsylvania style) use flat percentages. Either way, courts can deviate for extraordinary expenses or shared-time arrangements — this estimate is a planning tool, not a court order.
Keep pay stubs, tax returns, and childcare receipts — they back up every number in a modification hearing.
Job loss, a raise, or a shift in overnights can justify a modification — typically reviewed every 2–3 years or on material change.
Agreeing on parenting time and add-ons outside court often produces a fairer, more stable order.
Check whether your state uses income shares or flat percentages, and its specific caps and deviation rules.
⚠️ Important Note: This calculator provides estimates for general information only. Actual amounts vary by jurisdiction, provider, and individual circumstances. Consult a qualified professional (attorney, accountant, or licensed advisor) for advice specific to your situation.
Child support orders are set by state guidelines and individual judges. Use this tool to understand the mechanics and prepare for a conversation with a family law attorney — not as a substitute for one.