Your illustrative estimate
Step-by-step breakdown
How parenting time changes the estimate
| Time with Parent A | Illustrative net transfer | Direction |
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This table holds incomes and costs fixed and varies only Parent A's time share, so you can see the direction of the effect. Real state rules often use overnight thresholds and multipliers (for example, some states adjust the obligation once each parent has about 20% of overnights) — this illustration deliberately does not apply any threshold or multiplier, which is one more reason its figure will differ from an official worksheet.
Child Support Calculator: A Planning Estimate, Not a Court Order
If you are working out what child support might look like, you probably want one thing first: a realistic ballpark before you talk to a lawyer or walk into mediation. This calculator gives you that ballpark — and shows every step of its math, so you can see exactly where the number comes from and why it moves when an input changes.
One thing to be clear about up front: this is an estimate only. Real child support orders are set under state guidelines and by courts, and the rules vary widely from state to state. No online calculator — including this one — can give you the figure a court will order. Use this tool to plan, to prepare questions, and to sanity-check a conversation. For a figure you will rely on in a real case, use your state’s official calculator or worksheet and talk to a family law attorney licensed in that state.
How This Estimate Works
This tool uses a simplified version of the income-shares illustration, the approach most US states start from. The idea behind it is simple: children should receive roughly the same share of their parents’ combined income that they would have received if the parents still lived together. Here is the whole method, in plain steps:
- Add the incomes. Parent A’s monthly income plus Parent B’s monthly income gives the combined monthly income.
- Find the illustrative base obligation. The combined income is multiplied by an illustrative rate that rises with the number of children: 17% for one child, 25% for two, 29% for three, 31% for four, 33% for five, and 35% for six. These rates are a teaching illustration, chosen because they rise with each added child at a declining step, the way real schedules do. They are not any state’s official schedule, and no official national schedule exists.
- Add the extra monthly costs. Work-related childcare, the children’s health insurance premiums, and any other monthly costs you enter are added to the base obligation. Courts usually split these by income share too, so this tool does the same.
- Split by income share. Each parent’s share of the combined income is their income divided by the combined income.
- Apply the parenting-time cross-credit. Each parent is credited for the time the children spend with them, and the difference is what changes hands. In one line: net transfer = total obligation × (Parent A’s time share − Parent A’s income share). If the result is positive, Parent B pays Parent A. If it is negative, Parent A pays Parent B. If it is zero, there is no net transfer under this illustration.
That last step is why equal parenting time does not automatically mean zero support. If one parent earns much more than the other, the higher earner still transfers money even at 50/50, because the children cost the same in both homes while the incomes are not equal. The sensitivity table in your result shows this directly: change only the time share and watch the transfer move.
Worked Example (Check It by Hand)
Parent A earns $5,000 a month, Parent B earns $3,000 a month, there is one child, and Parent A has the child 70% of the time. No extra costs are entered.
- Combined income: $5,000 + $3,000 = $8,000
- Base obligation: $8,000 × 17% (one child) = $1,360
- Extra costs: $0, so the total obligation is $1,360
- Parent A’s income share: $5,000 ÷ $8,000 = 62.5%
- Net transfer: $1,360 × (70% − 62.5%) = $1,360 × 7.5% = $102.00 per month
So under this illustration, Parent B pays Parent A $102.00 a month — $1,224 a year — even though Parent A has most of the time and the higher income. The transfer is small because Parent A’s time share (70%) is close to Parent A’s income share (62.5%); the gap between those two percentages is the whole story. Try the same incomes at 50/50 in the calculator: the transfer jumps to $340 a month, because the gap widens to 25 percentage points.
A second example, with extra costs: Parent A earns $6,000, Parent B earns $2,000, two children, Parent A has the children full-time, and childcare costs $400 a month. Combined income is $8,000; the two-child rate is 25%, so the base is $2,000; adding $400 of childcare gives a $2,400 total; Parent A’s income share is 75%; the net transfer is $2,400 × (100% − 75%) = $600 a month, paid by Parent B.
What Courts Also Weigh (That This Tool Does Not)
A real guideline worksheet looks at far more than two incomes and a time percentage. Courts commonly consider which parent actually pays the health premium and the childcare bill (this tool shares those costs by income but does not credit a specific payer), other children a parent already supports, imputed income when a parent is voluntarily underemployed, taxes and mandatory deductions (some states run on net income, not gross), high-income caps or extrapolations, special medical or educational needs, travel costs for visitation, and case-specific deviations a judge may order up or down. If any of those apply to you, your real figure can differ a lot from this illustration — that is normal, and it is exactly why the official worksheet exists.
Common Mistakes
- Mixing gross and net income. If you enter one parent’s gross pay and the other’s take-home pay, the income shares — and therefore the whole answer — are wrong. Use the same basis for both parents, and check which basis your state uses before relying on any figure.
- Ignoring childcare and health insurance. These are often added on top of the base obligation and split by income share. Leaving them out understates the total, sometimes by hundreds of dollars a month.
- Assuming 50/50 means $0. It only means zero when the time share equals the income share. With unequal incomes, equal time still produces a transfer — see the worked example above.
- Treating an estimate as an order. Nothing on this page creates, changes, or enforces a support obligation. Only a court order does that, and only a court can modify an existing one.
- Using one state’s number in another state. A figure computed under one state’s rules has no standing in another state. The model, the income definition, and the parenting-time rule can all change at the state line.
- Forgetting that incomes change. A job loss, a raise, or a new schedule can be grounds to ask a court to review an order. An estimate made today is not a promise about next year.
Frequently Asked Questions
1. Is this child support calculator accurate? It is arithmetically accurate for the simplified illustration it states — every step is shown and can be checked by hand — but it is not a prediction of a court order. Real orders use state-specific schedules, thresholds, and adjustments this tool deliberately leaves out. Treat the result as a planning ballpark, then confirm it with your state’s official worksheet or a family law attorney.
2. How is child support usually calculated in the US? Most states use an income-shares approach: combine both parents’ incomes, look up a base obligation for that combined income and number of children, split it by each parent’s income share, then adjust for parenting time and add shared costs like childcare and health insurance. A few states instead apply a flat percentage to one parent’s income. Either way, the court has the final say and can deviate for special circumstances.
3. Does 50/50 custody mean no child support? Not necessarily. Under the income-shares illustration, the transfer depends on the gap between time share and income share. At 50/50 with equal incomes, the gap is zero and so is the transfer. At 50/50 with unequal incomes, the higher earner still pays — in the worked example above, $340 a month on $2,000 versus $6,000 incomes. Some states also apply their own shared-parenting thresholds and multipliers, which this illustration does not.
4. What counts as income for child support? It depends on the state. Commonly it includes wages, overtime, regular bonuses and commissions, self-employment income, and sometimes rental or investment income. Some states start from gross income and others from net income after taxes and mandatory deductions. Courts can also impute income to a parent who is voluntarily unemployed or underemployed. Enter figures on a consistent basis, and check your state’s definition before relying on any estimate.
5. Are childcare and health insurance included in child support? Usually they are handled as additions: work-related childcare and the children’s share of health premiums are added to the base obligation and divided by income share, with credit to whichever parent actually pays the bill. This calculator adds the costs you enter and shares them by income share, but it does not assign payer credit — another reason its figure differs from an official worksheet.
6. Can child support be changed after it is set? Yes, by asking the court — an existing order does not change on its own. Common reasons to request a review are a significant income change, a job loss, a change in the parenting schedule, or a change in a child’s needs. The threshold and process vary by state, and a new estimate from this calculator is not itself a modification.
Disclaimer
This calculator provides an educational estimate only. It is not legal advice, does not create an attorney-client relationship, and does not replace a court order, your state’s official child support guidelines or worksheet, or advice from a qualified family law attorney. Actual child support orders depend on state guidelines and courts, vary widely by state, and may differ substantially from this illustration, especially at very low or very high incomes, when either parent has other support obligations, or when special needs or extraordinary costs are involved. Do not rely on this estimate to make legal, financial, or parenting decisions without independent professional advice.