Alimony Calculator
A rough, educational estimate of monthly spousal support and its likely duration, using a generic guideline formula based on both spouses' incomes and the length of the marriage. Many states have no formula at all — treat this as orientation, not advice.
Reviewed by the CalcCafe editorial team · Last updated 18 July 2026 · How we test our tools
Example
One spouse grosses $9,000 a month, the other $3,000, after a 12-year marriage. The generic guideline takes 30% of the higher income ($2,700) minus 20% of the lower income ($600), for an estimated $2,100 per month. A common duration heuristic of half the marriage length suggests about 6 years of payments — roughly $151,200 in total. An actual award in your state could differ substantially in amount, duration or both, and some judges would order none at all on these facts.
How it works
Estimated monthly alimony = 30% of the higher earner's gross monthly income minus 20% of the lower earner's, floored at zero — a generic guideline pattern similar to the old AAML-style formulas some jurisdictions once used for temporary support. Estimated duration = half the length of the marriage, a common heuristic for short and mid-length marriages; marriages of 20 years or more are often treated differently, with many states allowing indefinite or long-term awards. The total is simply monthly × 12 × duration. No state is bound by this arithmetic: several use their own distinct formulas for temporary support, most leave final awards to judicial discretion over statutory factors, and a few restrict alimony sharply. The output is a conversation-starting estimate only.
Good to know
The 2017 Tax Cuts and Jobs Act changed alimony taxation for divorce or separation agreements executed after December 31, 2018: the payor can no longer deduct payments and the recipient no longer reports them as taxable income. Older agreements keep the old treatment unless modified to adopt the new rules. This shift effectively made alimony more expensive for payors, and negotiated amounts have adjusted accordingly.
Courts distinguish several types of support: temporary (pendente lite) support during the divorce itself, rehabilitative alimony for a defined period while the recipient retrains or re-enters the workforce, reimbursement alimony repaying contributions such as supporting a spouse through professional school, and permanent or long-term alimony, generally reserved for long marriages or recipients who cannot become self-supporting.
Where formulas do not control, judges weigh statutory factors: length of the marriage, each spouse's income and earning capacity, age and health, the marital standard of living, contributions as homemaker or to the other's career, child-care responsibilities and the ability of the payor to pay. Two judges applying the same factor list to the same facts can reach different awards — a key reason no calculator can promise accuracy.
Alimony is rarely fixed forever. Most awards are modifiable on a substantial change in circumstances (job loss, disability, genuine retirement) and typically terminate on the recipient's remarriage — and often on cohabitation with a new partner, depending on state law. Prenuptial and postnuptial agreements can waive or cap alimony entirely if properly executed. Because both the stakes and the state-to-state variation are large, use this page for orientation and have a family law attorney in your state evaluate any real situation.
Frequently asked questions
How is alimony actually determined?
It depends heavily on your state. Some states use formulas for temporary support, but most final awards come from judicial discretion over statutory factors: marriage length, each spouse's income and earning capacity, age, health, standard of living and contributions to the marriage. The generic 30%/20% guideline here is orientation only — no state is bound by it.
How long does alimony last?
A common heuristic awards support for roughly half the length of a short-to-medium marriage, which is what this calculator shows. Long marriages — commonly 20 years or more — may support indefinite or long-term awards in many states, while rehabilitative awards can be shorter. Duration rules differ sharply by state and by judge.
Is my data uploaded anywhere?
No — this calculator runs entirely in your browser. Income and marriage details never leave your device, and nothing is stored on any server.
Is this alimony calculator free?
Yes — completely free with no sign-up. It provides an educational estimate from a generic guideline, not legal advice; consult a family law attorney for your state's actual rules.
People also ask
Is alimony tax deductible?
Not for agreements executed after December 31, 2018 — under the Tax Cuts and Jobs Act the payor gets no deduction and the recipient owes no income tax on payments. Divorces finalized under the pre-2019 rules keep the old deductible/taxable treatment unless the agreement is modified to adopt the new law.
Does alimony stop if my ex remarries or cohabits?
Remarriage of the recipient terminates alimony in nearly every state. Cohabitation with a new partner also suspends or ends support in many states, though the standard of proof varies. The payor's genuine retirement can be grounds for modification as well.
Can a prenup waive alimony?
Generally yes — a properly executed prenuptial or postnuptial agreement can waive or limit spousal support in most states, provided it was entered voluntarily with fair disclosure and is not unconscionable at enforcement. Some states let courts override waivers that would leave a spouse destitute.
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Sources & references
These tools follow our methodology and provide educational estimates only — verify important figures with a qualified professional.