Alimony Calculator
Estimates monthly spousal support payments from each spouse's income, marriage length, alimony type, and age adjustment. Useful for divorce planning, mediation prep, or sanity-checking attorney quotes — not enforceable without a court order.
Last updated: May 2026
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About this calculator
Alimony (also called spousal support or maintenance) compensates the lower-earning spouse after divorce to help maintain a comparable standard of living. The formula used here is: monthly_alimony = max(0, (higherIncome − lowerIncome) × alimonyType × ageAdjustment × min(1, marriageDuration / 10)) / 12. Variables: higherIncome and lowerIncome (annual gross incomes of payer and recipient), alimonyType (0.25 rehabilitative, 0.30 temporary, 0.35 permanent — the share of income difference targeted), ageAdjustment (1.0 under 40, 1.1 ages 40–50, 1.2 over 50 — recognizes reduced re-employment capacity), marriageDuration (years, capped at 10 in the formula). The min(1, marriageDuration/10) factor scales the award linearly from 0% support after 0 years to 100% of the formula amount after 10 years, then plateaus. The max(0, …) floor prevents a negative result when the recipient out-earns the payer. Edge cases: this formula is highly simplified — actual state law varies dramatically. Massachusetts and Texas use formula-based statutes; California, New York, and Florida give judges broad discretion; some states (Indiana, Mississippi) rarely award alimony at all. The formula also ignores standard of living during marriage, contributions to the other spouse's career, retirement-account division, tax treatment (alimony from agreements signed after 2018 is not federally taxable), and remarriage termination provisions.
How to use
Example 1: Payer earns $120,000/year, recipient earns $40,000/year, married 8 years, rehabilitative (0.25), under 40 (1.0). Step 1 — income gap: $120,000 − $40,000 = $80,000. Step 2 — apply type and age: $80,000 × 0.25 × 1.0 = $20,000/year. Step 3 — duration factor: min(1, 8/10) = 0.8. Step 4 — annual: $20,000 × 0.8 = $16,000. Step 5 — monthly: $16,000 / 12 = $1,333/month. Verify: 25% of the gap × 80% duration factor = 20% of gap, divided by 12 — yields ~$1,333, matching the calculation. Example 2: Payer earns $150,000, recipient earns $30,000, married 15 years (caps at 10), permanent (0.35), age 52 (1.2). Step 1: $150,000 − $30,000 = $120,000. Step 2: $120,000 × 0.35 × 1.2 = $50,400. Step 3: min(1, 15/10) = 1.0 (capped). Step 4: $50,400 × 1.0 = $50,400/year. Step 5: $50,400 / 12 = $4,200/month. Verify: long marriage and older recipient produce the highest support, consistent with permanent-maintenance norms.
Frequently asked questions
How is alimony calculated during a divorce settlement?
Alimony is calculated by examining the income gap between spouses, the length of marriage, and the recipient's financial need. This calculator uses a percentage of the income difference (25–35% depending on alimony type) scaled by marriage duration and an age adjustment, then converted to monthly. Courts may also consider standard of living during marriage, each spouse's age and health, contributions like homemaking or supporting the other's career, and the payer's ability to pay. Many states (Massachusetts, Texas, Illinois) use statutory formulas, while others (California, New York, Florida) leave the amount entirely to judicial discretion. Always check your state's specific approach.
How long do alimony payments typically last after a divorce?
Duration is usually tied to the length of the marriage. Short marriages under five years may result in temporary or no support. Moderate-length marriages of 10–15 years often produce support lasting half the marriage duration. Marriages over 20 years — especially where one spouse left the workforce — can result in long-term or indefinite support, sometimes until retirement age. Most alimony orders include a termination clause triggered by the recipient's remarriage, cohabitation with a romantic partner, or a significant change in either party's financial circumstances. Massachusetts's 2011 Alimony Reform Act, for example, ties duration to specific marriage-length brackets and ends most orders at the payer's full retirement age.
Can alimony be modified after the divorce is finalized?
Yes — alimony can typically be modified if either party experiences a substantial change in circumstances such as job loss, significant income increase, recipient remarriage, or a serious health event. The party requesting modification must file a motion with the court and provide evidence of the change. Some divorce decrees include automatic modification clauses tied to cost-of-living indexes or specific events like the recipient finishing school. Consulting a family-law attorney before seeking modification is strongly advisable, since courts apply different standards depending on the original order's terms. Note that lump-sum or property-settlement alimony usually cannot be modified — only periodic spousal support is typically subject to change.
What are common mistakes when estimating alimony with this calculator?
Using net income instead of gross income produces an understated figure since most state guidelines use gross. Forgetting that this calculator caps the duration factor at 10 years — so a 25-year marriage produces the same result as a 10-year one — misrepresents long-marriage awards. Confusing alimony type categories is common: temporary alimony lasts only during the divorce proceedings (not after), rehabilitative supports retraining, and permanent supports indefinite need. Ignoring state-specific caps (Massachusetts limits general-term alimony to 30–35% of income difference) leads to inflated estimates. Forgetting that post-2018 alimony agreements are not federally tax-deductible to the payer or taxable to the recipient skews after-tax planning.
When should I NOT use this alimony calculator?
Never use a generic calculator to set or modify a legal alimony order — only a court order is enforceable. The output is not legal advice and ignores state-specific guidelines. High-net-worth divorces involving business interests, stock options, deferred compensation, or significant separate property require professional valuation, not formula. Short marriages (under three years) often produce no alimony at all in many states. Same-sex marriages predating Obergefell may have complex retroactivity questions about marriage duration. International divorces involving foreign assets, foreign tax treatment, or non-U.S. courts trigger conflict-of-laws analysis this tool cannot perform. For any actual divorce, retain a family-law attorney licensed in your jurisdiction.