How is the alimony amount estimated?

A widely used guideline takes a percentage of the higher earner's income and subtracts a smaller percentage of the lower earner's income — the classic 30%/20% differential. The result is capped so the recipient's total income does not exceed a set share (commonly 40%) of the parties' combined income.

How is the duration of support estimated?

Many jurisdictions tie duration to marriage length: a fraction of the years married, increasing in long marriages, with marriages over roughly twenty years sometimes treated as indefinite or until retirement. This tool applies a stepped multiplier as an illustration.

Are these the official numbers for my state?

No. Only a handful of states publish formulaic guidelines, and many use the open-ended statutory factors instead — need, ability to pay, age, health, and standard of living. Treat the output as a negotiation anchor, not a court order.

Does this account for taxes or child support?

No. Since 2019, federal alimony is neither deductible nor taxable for new orders, and child support is calculated separately and usually takes priority. Model child support first, then revisit spousal support against the remaining income.

What is the 40% combined-income cap?

Several guideline formulas prevent the recipient's post-support income from exceeding about 40% of the couple's combined income, so the higher earner never ends up worse off than the recipient. This tool applies that cap and tells you when it binds.

Spousal Support / Alimony Calculator

A spousal support calculator estimates both the monthly amount of alimony and its likely duration from the two key drivers most guideline formulas share: the income gap between the spouses and the length of the marriage. While only some states publish a formula, the patterns below are common negotiation anchors used by family law practitioners to set realistic expectations before mediation.

How it works

For the amount, the tool uses the classic income-differential formula: take roughly 30% of the higher earner’s gross income and subtract about 20% of the lower earner’s income. The positive difference is the indicated monthly support. A cap then applies — the recipient’s total income (their own plus support) is held to no more than 40% of the couple’s combined income — which prevents the formula from over-shifting income.

For the duration, the tool multiplies the years married by a stepped factor that grows with longer marriages: shorter marriages yield a small fraction of their length, mid-length marriages a larger fraction, and very long marriages can be treated as long-term or indefinite, often until retirement age.

Amount = max(0, 0.30 × high income − 0.20 × low income), capped at 40% of combined income. Duration ≈ years married × a multiplier that rises with marriage length.

Example and notes

If one spouse earns $8,000 and the other $3,000 per month, the differential formula indicates 0.30 × 8000 − 0.20 × 3000 = 2400 − 600 = $1,800 per month. The cap check confirms the recipient’s $3,000 + $1,800 = $4,800 stays under 40% of $11,000 combined ($4,400) — here the cap binds, trimming support to $1,400.

These are illustrative formulas, not the law of any single state. Real awards weigh need, earning capacity, health, age, and standard of living, and judges retain wide discretion. Model child support separately and remember that post-2018 alimony has no federal tax effect.