California Child Support Calculator
Estimate California guideline child support in under a minute
Estimate guideline child support using the same statewide formula San Diego judges apply under Family Code section 4055, updated for the law change that took effect September 1, 2024.
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Taxes and deductions (optional)
Taxes and deductions (optional)
Parenting time (timeshare) has a major effect on the guideline amount.
Guideline software is only as good as the inputs, and income, timeshare, and deductions are exactly where child support cases are won or lost. Fair Cadora's board-certified family law specialists handle child support in San Diego every day.
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Disclaimer: This calculator is for general informational purposes only and is not legal advice. Results are estimates based on the California statewide uniform guideline (Family Code section 4055) with simplified tax assumptions, and they are not the amount a court will order. Actual guideline calculations depend on complete tax and income information and are performed with court-certified software. Use of this tool does not create an attorney-client relationship with Fair Cadora, APC. Consult a qualified San Diego family law attorney about your specific circumstances.
How child support is calculated in California
Every California court, including the San Diego Superior Court, uses one statewide formula set out in Family Code section 4055:
Family Code section 4055, as updated by SB 343 effective September 1, 2024. Here is what each piece means.
The base monthly amount for one child. Multiplied for more children: 1.6x for two, 2x for three, up to 2.86x for ten.
The share of combined income devoted to the children. Set by income tables in the statute, then adjusted for parenting time.
The higher-earning parent's net monthly disposable income: gross income minus taxes and allowed deductions.
The percentage of time the higher earner has primary physical responsibility for the children. More time means lower support.
Both parents' net monthly disposable incomes added together. Drives which K bracket applies.
One parent nets $5,870 a month with 30% parenting time, the other nets $3,413. K comes out to 0.325, and the two-child multiplier is 1.6. If the result is ever negative, the lower earner pays that amount instead.
Source: California Family Code § 4055. Net incomes here are estimates for illustration. Try your own numbers in the calculator above.
In plain English, the formula looks at three things: how much each parent earns after taxes and certain deductions (net disposable income), how much of both parents’ combined income should be devoted to the children (the K factor), and what percentage of time the higher-earning parent has the children (timeshare). The more the higher earner makes relative to the other parent, and the less time that parent spends with the children, the higher the support amount.
If you have been lying awake wondering what support might look like for your family, running your real numbers is often the fastest way to feel steadier. As Fair Cadora partner Lauren Fair puts it on her podcast, The Sensible Split:
"Questions without answers turn into fear. Fears, oftentimes, are just simply questions that require answers."
The formula changed on September 1, 2024, when Senate Bill 343 took effect. The update revised the K factor tables, expanded the low-income adjustment so it now applies presumptively to parents earning less than full-time minimum wage, and changed how add-on expenses like child care are divided, from an automatic 50/50 split to a split in proportion to each parent’s net income. This calculator uses the current post-SB 343 formula. If your support order was calculated before September 2024, the number that comes out today may be different, which can be grounds to request a modification.
What counts as income for child support
California defines income broadly. Wages, salaries, commissions, bonuses, self-employment earnings, rental income, interest, dividends, unemployment and disability benefits, and even recurring gifts can all count. Courts can also impute income to a parent who is unemployed or underemployed by choice, meaning support is calculated on what that parent could earn rather than what they report. From gross income, the law then subtracts state and federal taxes, mandatory retirement contributions and union dues, health insurance premiums, and child or spousal support actually paid in other cases to arrive at net disposable income under Family Code section 4059.
On top of the base guideline amount, courts add mandatory add-ons: work-related child care and the children’s uninsured health care costs. Since the 2024 law change these are divided in proportion to each parent’s net income rather than split evenly.
Know your number before you negotiate
Here is something most people do not realize when they start worrying about child support: the vast majority of these cases never end with a judge picking a number at trial.
"About 95%-ish of family law cases settle. It's just a question of where in the process that they settle."
That changes how you should use a tool like this. Because the guideline formula is mandatory, both attorneys and mediators negotiate in its shadow. Walking into mediation or a settlement conversation already knowing your realistic guideline range keeps you from anchoring to a number that is far too high or too low, and it takes much of the emotion out of the money conversation. That matters beyond the dollars, because the research and Lauren’s two decades in family law point to the same conclusion:
"The less conflict between parents, the better kids do in divorce."
A clear, formula-based number gives both parents something objective to talk about instead of something to fight about.
Frequently Asked Questions
How accurate is this calculator?
It applies the actual statutory formula, including the current K factor tables, the multiple-children multipliers, and the low-income adjustment, and it estimates taxes using current federal and California rates. Courts, however, use certified software (such as Xspouse software or the official California Guideline Child Support Calculator) loaded with your exact tax details, and judges have discretion to deviate in limited situations. Treat this as a realistic starting point, not a final answer.
How much is child support for one child in California?
There is no flat rate. The amount depends on both parents’ net incomes and the timeshare. As a rough illustration, if one parent nets $6,000 a month, the other nets $3,000, and the children are with the higher earner 30% of the time, guideline support for one child comes out to several hundred dollars per month, and it scales up with income. Use the calculator above with your own numbers.
Does 50/50 custody mean no child support?
No. Equal parenting time reduces support but does not eliminate it when the parents earn different amounts. With a 50/50 schedule, the formula still requires the higher earner to pay support so the children have comparable standards of living in both homes. Support only approaches zero when both timeshare and incomes are close to equal.
What changed under SB 343 in 2024?
Three main things: the K factor tables that set how much combined income is allocated to the children were revised, the low-income adjustment became presumptive and now applies to parents earning less than full-time minimum wage (roughly $2,900 net per month in 2026), and mandatory add-ons like child care are now divided in proportion to income instead of 50/50. Orders calculated under the old formula can often be modified.
Can parents agree to a different amount?
Yes, within limits. Parents can stipulate to an amount above guideline, or below guideline if the court finds the agreement is in the children’s best interest, both parents know their rights, and neither is on public assistance. A judge must still approve it.
When can child support be changed?
Either parent can request a modification when there is a change in circumstances: a job loss or pay change, a new custody schedule, a new child, or a change in the law itself, such as the 2024 formula update. Support generally continues until a child turns 18, or 19 if still in high school and living at home.
Is this calculator specific to San Diego?
The formula is the same statewide, so the math works anywhere in California. What varies locally is practice: how the San Diego Superior Court and the local Department of Child Support Services handle filings, hearings, and enforcement. That is where working with a San Diego child support attorney makes a difference.
