SupportDecode

Updated for 2026 state guidelines

Child support calculators you can check

Child support rules are public law, but the math behind them is hard to find and easy to get wrong. This site runs the real state formulas and shows its work. Every rate, cap, and table links to an official source, with the date it took effect and the date we last checked it.

Open the calculatorJump to your state ↓

Everything here is an estimate, not legal advice. The court or state agency calculation controls.

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Choose your state

Open the current formula, source notes, worked example, and official links for your jurisdiction.

Compare child support rules and verification evidence on the US map →

Popular custody schedules

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Thanksgiving and winter custody calendars

See the 2026 overnight examples, check holiday overlaps, and use your actual school dates where the planning convention differs from your order.

Start here

Child support calculatorSee which guideline model all 50 states and DC use, compare a standard scenario across them, and run a full estimate for any of the 51 jurisdictions.Open the calculator →

Start with your situation

Not sure which calculator you need? Pick what is happening and follow a short path through the relevant tool, explanation, and official source.

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State calculators

All 51 jurisdictions have source-linked pages covering child support, arrears and interest, wage garnishment limits, and alimony or spousal support. Calculators state their supported inputs and limits. Where we cannot responsibly calculate an amount, a rules guide explains the factors and points to official resources instead.

Coverage includes all 50 states plus Washington, DC. Each research pack is reviewed against official worksheets and primary legal sources.

51

Jurisdictions mapped: 50 states plus DC

51

Jurisdictions with calculators and source-linked rules guides

553

Official sources cited, each with a checked date

510

Engine regression scenarios run on every build, including fail-closed checks; 61 match official numeric outputs within the published verification tolerance

Parenting time and money tools

Overnights drive many support formulas, so the schedule tools and the money tools share the same math. All of them run in your browser; nothing you type is stored or sent anywhere.

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How we keep the numbers honest

A number without a source is a guess. Ours come from statutes, court rules, and official guideline tables, and each page lists exactly which ones. When a state has no formula, we say so instead of inventing one. When a rule changes, the fix gets a dated entry in the update log, never a silent edit.

The formulas are also regression-tested: 510 scenarios run through the real state formulas on every build, 61 of them match official calculator outputs within the published verification tolerance, and 152 still await an official cross-check. We publish that pending count instead of claiming universal accuracy.