Alimony Calculator - Free Online Tool

Estimate spousal support payments using 10 state-specific formulas

Divorce is one of the most financially disruptive events a person can face, and understanding potential alimony — also known as spousal support or spousal maintenance — is critical for both parties as they plan their financial futures. Our free Alimony Calculator applies ten widely-recognized formulas simultaneously, giving you a realistic range of estimates without requiring you to hire an attorney just to understand the ballpark figures. Alimony is a legal obligation for one spouse to provide financial support to the other after separation or divorce. Its primary purpose is to limit the economic unfairness that can occur when one spouse earns significantly more than the other, or when one spouse sacrificed career advancement to support the household or raise children. Courts consider many factors when awarding alimony, including the length of the marriage, each spouse's income and earning capacity, the standard of living established during the marriage, and the age and health of both parties. Because alimony law varies dramatically by state — and even by county — no online calculator can predict exactly what a judge will award. However, understanding the formulas that courts and practitioners use as starting points gives you an enormous informational advantage when negotiating a settlement or preparing for litigation. Knowing that the AAML formula suggests $1,200 per month while the Illinois guideline suggests $950 helps you and your attorney set realistic expectations. This calculator implements ten formulas: the AAML (American Academy of Matrimonial Lawyers) guideline, which is the most widely cited general-purpose formula; the California formula based on net incomes; the Illinois statutory guideline with its precise duration multiplier table; the Texas formula with its statutory cap; the Kansas sliding-scale formula; the Massachusetts General Term Alimony formula; the Pennsylvania formula; the Arizona duration-weighted formula; the Virginia formula; and the General one-third rule used as a rough cross-check. To get the most accurate estimate, you should gather your gross and net monthly incomes and your spouse's gross and net monthly incomes. The gross income is your total income before taxes and deductions; the net income is what you actually take home after taxes. Different formulas weight these differently — for example, AAML and Texas use gross income, while California, Illinois, and Pennsylvania use net income. The length of your marriage in years is also critical because most formulas tie alimony duration directly to how long you were married. Use the income period toggle to enter figures as monthly or annual amounts — the calculator converts them automatically. Advanced inputs let you account for capital gains and investment income as well as income already allocated to child support, which some formulas require as deductions before calculating alimony. Once you enter your figures, the calculator instantly shows results for all ten formulas, a comparison bar chart, a donut chart showing each party's post-alimony income share, and a duration comparison across formulas. Remember that this tool provides educational estimates only. Actual alimony is determined by a judge who considers your specific circumstances, local precedent, and factors that no formula can fully capture. Always consult a licensed family law attorney in your jurisdiction before making any legal or financial decisions.

Understanding Alimony Calculations

What Is Alimony?

Alimony (also called spousal support or spousal maintenance) is court-ordered financial support paid by one ex-spouse to the other after separation or divorce. Its purpose is to reduce economic disparity when one spouse earns significantly more, or when one spouse gave up career opportunities to support the household. There are several types: rehabilitative alimony (temporary support while the lower-earning spouse retrains or finds work), permanent or long-term alimony (common after long marriages), reimbursement alimony (repaying a spouse who supported the other through school), and transitional alimony (covering short-term adjustment costs). Courts consider income, marriage length, standard of living, age, health, and earning capacity when setting awards.

How Is Alimony Calculated?

No single national formula governs alimony. Each state has its own statutory guidelines, and many states give judges broad discretion. Common formula approaches include: the AAML standard (30% of payor gross minus 20% of payee gross, annualized, capped at 40% of combined income); the California formula (40% of payor net monthly minus 50% of payee net monthly); the Illinois statutory table (33.3% of payor net minus 25% of payee net, with a duration multiplier from 0.20 to permanent based on marriage years); the Texas approach (20% of payor gross annual capped at $6,000/year); and the General one-third rule ((payor net minus payee net) divided by 3). Duration is typically a percentage of marriage length or follows statutory brackets.

Why Does It Matter?

Understanding alimony estimates before entering negotiations or litigation gives both parties an informational foundation for fair settlement discussions. For the payor, knowing the likely payment range helps with post-divorce budgeting, retirement planning, and evaluating the cost-benefit of settlement versus trial. For the recipient, it clarifies what financial support to expect and how much time there is to rebuild financial independence. Alimony also has significant tax implications — under current US federal law (for divorces finalized after 2018), alimony is neither deductible for the payor nor taxable income for the recipient, which represents a major shift from prior law. Understanding the full picture is essential for informed decision-making.

Limitations of This Calculator

This calculator provides educational estimates based on commonly used formulas, not legal advice. Actual alimony awards depend on state-specific statutes, local court customs, and judicial discretion. Judges consider factors that formulas cannot capture: the health and age of each party, the standard of living during the marriage, contributions as a homemaker or caregiver, fault (in states that consider it), premarital agreements, and each spouse's actual earning capacity versus current income. Some states have abolished permanent alimony entirely. Results should be treated as a starting-point range, not a prediction. Always consult a licensed family law attorney in your jurisdiction before making any legal decisions.

Alimony Calculation Formulas

AAML Income Difference Method

Monthly = (0.30 × Payor_Gross − 0.20 × Payee_Gross) / 12

The American Academy of Matrimonial Lawyers formula calculates alimony as 30% of the payor's gross income minus 20% of the payee's gross income, divided by 12 for a monthly figure. The result is capped so the payee's total income does not exceed 40% of combined gross.

California Net Income Method

Monthly = 0.40 × Payor_Net_Monthly − 0.50 × Payee_Net_Monthly

California's guideline takes 40% of the payor's net monthly income and subtracts 50% of the payee's net monthly income. If the result is negative, no alimony is awarded.

Illinois Statutory Formula

Monthly = (0.333 × Payor_Net − 0.25 × Payee_Net) / 12

Illinois uses 33.3% of the payor's net annual income minus 25% of the payee's net annual income, capped at 40% of combined net income. Duration is set by a statutory multiplier table based on marriage length.

Duration-Based Estimate

Duration = Marriage_Years × Multiplier (0.20 to 1.0+)

Most formulas tie alimony duration to marriage length using a multiplier. Short marriages (under 5 years) use 0.20–0.30; mid-length (5–15 years) use 0.50; long marriages (20+ years) may result in indefinite or permanent alimony.

Alimony Reference Tables

State Alimony Approaches

Overview of how different states approach alimony calculation, ranging from strict statutory formulas to broad judicial discretion.

State/Formula	Approach	Income Basis	Cap
AAML	Formula-based	Gross income	40% of combined gross
California	Formula-based	Net income	None (can be $0 minimum)
Illinois	Statutory formula + table	Net income	40% of combined net
Texas	Statutory cap	Gross income	$6,000/year maximum
Kansas	Sliding scale	Income difference	Tiered by income level
Massachusetts	Formula-based	Available income	30–35% of income difference
Pennsylvania	Judicial discretion	Net income	Court-determined
Arizona	Duration-weighted	Income difference	Factor up to 0.5
Virginia	Formula-based	Gross income	None specified
General 1/3 Rule	Rule of thumb	Net income	None

Duration Guidelines by Marriage Length

General guidelines for how long alimony payments last based on the length of the marriage, varying by jurisdiction.

Marriage Length	Typical Duration	Common Type
Under 3 years	0–30% of marriage length	Transitional / none
3–5 years	30–50% of marriage length	Rehabilitative
5–10 years	50% of marriage length	Rehabilitative / limited term
10–15 years	50–75% of marriage length	Limited term / general term
15–20 years	75–100% of marriage length	General term
20+ years	Indefinite / permanent	Permanent / lifetime

Worked Examples

AAML Formula: 15-Year Marriage, $120K vs $50K Income

The payor earns $120,000/year gross and the payee earns $50,000/year gross. The marriage lasted 15 years. Calculate alimony using the AAML formula.

Calculate 30% of payor gross: 0.30 × $120,000 = $36,000

Calculate 20% of payee gross: 0.20 × $50,000 = $10,000

Annual alimony: $36,000 − $10,000 = $26,000

Monthly alimony: $26,000 / 12 = $2,167

Check 40% cap: Payee total = $50,000 + $26,000 = $76,000; Combined = $170,000; 40% = $68,000 — cap applies

Capped annual: $68,000 − $50,000 = $18,000 → Monthly: $1,500

Duration: 15 years × 0.75 (10–20 year bracket) = 11.25 years

The AAML formula yields approximately $1,500/month for 11.25 years, with total alimony paid of approximately $202,500. The 40% income cap reduced the payment from the uncapped $2,167/month.

California Formula: Comparing Temporary vs Long-Term Support

Payor net monthly income: $7,000. Payee net monthly income: $2,500. Marriage: 8 years.

Calculate 40% of payor net: 0.40 × $7,000 = $2,800

Calculate 50% of payee net: 0.50 × $2,500 = $1,250

Monthly alimony: $2,800 − $1,250 = $1,550

Duration: Under 10 years → 50% of marriage length = 4 years

Total cost: $1,550 × 48 months = $74,400

Under the California formula, alimony would be approximately $1,550/month for 4 years, totaling $74,400. For marriages over 10 years, the duration would be open-ended per California guidelines.

How to Use This Calculator

Select Income Period

Choose whether you will enter incomes as monthly or annual figures. Monthly is typically easier if you know your paycheck amounts. The calculator automatically converts to the other period.

Enter Both Spouses' Incomes

Input the payor's (higher earner's) gross and net incomes and the payee's (lower earner's) gross and net incomes. Gross is before taxes; net is take-home pay. Both are needed because different state formulas use different income bases.

Enter Marriage Length

Type the number of years you were married. Decimals are supported (e.g., 7.5 years). This is critical because nearly all formulas tie alimony duration to how long you were married, and some formulas adjust the amount as well.

Review All Formula Results

The results panel shows estimates from all 10 formulas simultaneously — monthly payment, duration, and total cost. Use the comparison bar chart to see the spread between formulas, and the income donut chart to visualize each party's share of combined income after alimony payments.

Frequently Asked Questions

Which alimony formula should I use?

The formula that applies to you depends on the state where your divorce is filed. If you live in Illinois, a judge will follow the Illinois statutory guideline; in Texas, the Texas statutory cap applies. If your state is not listed or uses judicial discretion (like Pennsylvania or Virginia), the AAML formula is the most widely cited general-purpose guideline used by practitioners nationwide. Because most states have some discretion built in, looking at the full range of estimates — from the low to the high — gives you the best sense of what is negotiable. Always confirm the applicable formula with a family law attorney in your state.

What is the AAML formula for alimony?

The AAML (American Academy of Matrimonial Lawyers) formula calculates monthly alimony as 30% of the payor's gross annual income minus 20% of the payee's gross annual income, divided by 12. There is an income cap: the payee's total income after receiving alimony cannot exceed 40% of the combined gross income of both parties. Duration follows four brackets: marriages under 3 years use 30% of the marriage length; 3–10 years use 50%; 10–20 years use 75%; and marriages of 20 or more years may result in indefinite or permanent alimony. This formula is not law in any specific state but is widely used as a reasonable starting point.

How is alimony duration determined?

Alimony duration is almost always tied to the length of the marriage, though the exact rules vary by state. Short marriages (under 5 years) typically result in brief or no alimony. Mid-length marriages (5–15 years) usually result in rehabilitative alimony lasting a fraction of the marriage length — commonly 30% to 70%. Long marriages (15–20+ years) can result in long-term or even permanent alimony, especially when one spouse has been out of the workforce for many years. Illinois has one of the most precisely codified duration tables, specifying a multiplier for each year range. This calculator shows duration estimates for each formula so you can compare across jurisdictions.

Is alimony taxable income?

Under the Tax Cuts and Jobs Act (TCJA) signed in December 2017, alimony rules changed for divorce or separation agreements finalized after December 31, 2018. For these agreements, alimony payments are no longer deductible by the payor and are no longer included in the recipient's taxable income. For divorces finalized before January 1, 2019, the old rules apply: the payor can deduct alimony, and the recipient must include it as taxable income. This is a significant consideration when negotiating settlements, as the after-tax cost and benefit of alimony differ substantially depending on which tax regime applies. Always consult a tax professional alongside your family law attorney.

Can alimony be modified after the divorce?

Yes, in most states alimony can be modified if there is a substantial change in circumstances after the original award. Common grounds for modification include a significant increase or decrease in either party's income, the recipient remarrying or cohabitating with a new partner (which terminates alimony in many states), either party's retirement, or a serious health change affecting earning capacity. Some divorce agreements include automatic termination clauses tied to specific events. Courts require evidence of a material change, not just routine income fluctuations. Prenuptial or postnuptial agreements that address alimony can also limit modification rights. Review your specific state's statutes and your divorce decree for the exact standards.

What is the 40% income cap in alimony calculations?

The 40% income cap is a guard rail used by the AAML formula and the Illinois statutory guideline to prevent alimony from resulting in the recipient earning more than the payor. Specifically, after receiving alimony, the recipient's total income (their own income plus the alimony payment) cannot exceed 40% of the combined gross (AAML) or combined net (Illinois) income of both parties. This cap is enforced automatically in this calculator — if the formula result would push the recipient above 40%, the payment is reduced to the maximum allowed. Many other states use similar principles informally, even if not codified as a hard cap.