Estimate child support
your state's official formula.
Income Shares · Percentage of Income · Melson Formula — 3 models, 10 verified state calculators, side-by-side state comparisons. Free, no registration.
- Income Shares
- 42
- Percentage
- 6
- Melson
- 3
- Live calculators
- 10
The 3 Child Support Formula Models
Every US state uses one of three models to calculate child support. Your state's model determines which parent's income matters — and how much.
42 States
Both parents' incomes are combined. A support obligation is determined from a schedule based on total income, then split proportionally between parents.
Typical range (1 child): 17–22% of combined income
View 42 states →6 States
A fixed percentage of the non-custodial parent's income is applied. Simpler than Income Shares — only the obligor's income matters.
Typical range (1 child): 14–20% of obligor income
View 6 states →3 States
A three-step formula: first ensures each parent's self-support needs, then calculates primary child support, then adds a standard-of-living adjustment (SOLA).
States: DE, HI, MT
View 3 states →Interactive Calculators
Phase 1: State-specific calculators available for the 10 largest states by population.
What Factors Affect Child Support?
- 💰
Both Parents' Incomes
Most states consider gross or net income of both parents.
- 🏠
Parenting Time
40%+ overnight time with the non-custodial parent typically triggers a credit.
- 👶
Number of Children
Obligations scale with each additional child, but not proportionally.
- 🏥
Health Insurance
The parent paying premiums typically gets a credit against the obligation.
- 🏫
Childcare Costs
Work-related childcare expenses are typically split proportionally.
- 📚
Educational Expenses
Private school and extraordinary educational costs may be added to the base.
Guides
Child Support Formulas Explained
Income Shares vs Percentage vs Melson — what each means for you.
How to Modify a Child Support Order
When and how to request modification after a substantial change.
Interstate Child Support: UIFSA
When parents live in different states — which state controls?
Understanding Imputed Income
Courts can assign income to voluntarily unemployed parents.
Deviation Factors by State
Circumstances that allow judges to depart from guideline amounts.
Important Disclaimer
This calculator provides estimates for informational purposes only. Actual child support amounts may differ based on judicial discretion, deviation factors, and current state guidelines. Consult a family law attorney in your state for legal advice.
Frequently Asked Questions
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Research
Original analysis from our editorial team, every statistic derived from our own database. See all research.
Three Formulas, One Country: How US Child Support Calculations Diverge by State
42 of 51 US states use Income Shares, 6 use Percentage of Income, and 3 use the Melson self-support-reserve model — a mechanical split that produces radically different outcomes at identical incomes.
ResearchWhy Iowa Collects 68.4% of Child Support While Mississippi Collects 49.3%
PlainChildSupport's enforcement data shows a 19.1 percentage-point gap between the best-performing and worst-performing US states on child support collection rate — a structural divergence that compounds to billions in unpaid support.
ResearchOnly 10 of 51 States Publish Verified Child Support Calculators
Of 51 US jurisdictions, only 10 publish official calculators that PlainChildSupport has verified against statute. The other 41 rely on PDF worksheets, third-party tools, or formulas parents must execute themselves.
Related Guides
Editorial context for the plainchildsupport dataset — methodology, comparisons, and deep dives into the underlying records.