How much alimony (spousal support) will you pay or receive? Estimate monthly and total alimony with this free calculator using common income-based formulas and marriage-duration guidelines.
Mode A uses the Massachusetts-style formula: monthly = (30% of payer income − 50% of recipient income) ÷ 12, floored at $0. Duration follows the one-third rule: 1 year of support per 3 years of marriage.
Mode B takes a percentage of the income gap: monthly = (payer income − recipient income) × percentage ÷ 12. A common guideline is 25–40% of the difference; 25% is the default here.
Inputs: Payer earns $120,000/year, recipient earns $40,000/year, 10-year marriage.
Calculation: 30% of $120,000 = $36,000.00. 50% of $40,000 = $20,000.00. Monthly = ($36,000.00 − $20,000.00) ÷ 12 = $1,333.33. Duration = 10 × 12 × 0.33 = 39.6 months (≈ 3 yr 4 mo).
Inputs: Payer earns $60,000/year, recipient earns $80,000/year.
Calculation: 30% of $60,000 = $18,000.00. 50% of $80,000 = $40,000.00. Monthly = ($18,000.00 − $40,000.00) ÷ 12 = −$1,833.33, which is negative.
Inputs: Payer earns $120,000/year, recipient earns $40,000/year, 25% rate, 5-year marriage.
Calculation: Income difference = $120,000 − $40,000 = $80,000.00. Monthly = $80,000.00 × 25% ÷ 12 = $1,666.67. Duration = 5 × 12 × 0.33 = 19.8 months.
Note: These verified examples use common formula-based guidelines. Actual awards vary widely by state, judge, and the specific facts of a case — use your own numbers for the most relevant estimate.
Variables: Payer Income = higher earner's annual gross income · Recipient Income = lower earner's annual gross income · Percentage = 10%–40% of the income gap (25% default) · Marriage Years = length of the marriage at divorce
Rules of thumb: Negative results in Mode A → $0.00 alimony · Marriages under 1 year → 0-month duration · Duration display rounds the leftover months (e.g., 39.6 months ≈ 3 years 4 months)
Pick Income Differential Formula for a Massachusetts-style estimate (30% of payer income minus 50% of recipient income), or Percentage of Income Difference to apply a rate you choose (10%–40%) to the income gap.
Use each spouse's gross annual income from all sources and the total number of years the marriage lasted. Fractions of years (e.g., 7.5) are supported.
The calculator shows your monthly payment, the support duration from the one-third rule, the total obligation, and a step-by-step breakdown of every computation so you can verify the math yourself.
This calculator applies two of the most common income-based approaches used in family law. In Mode A, the Massachusetts-style formula takes 30% of the payer's annual income, subtracts 50% of the recipient's annual income, and divides by 12 to get a monthly payment. If the result is negative — meaning the recipient out-earns the payer — alimony is set to $0.00.
In Mode B, you apply a percentage (10%–40%, 25% by default) to the difference between the two annual incomes, then divide by 12. The payment duration follows the one-third rule: one year of support for every three years of marriage (marriage years × 12 × 0.33). The total obligation is simply the monthly amount multiplied by the number of months.
Monthly = (0.30 × payer income − 0.50 × recipient income) ÷ 12. Negative results are floored to $0.00.
Monthly = income difference × percentage ÷ 12. Higher percentages suit longer marriages and larger lifestyle gaps.
Duration = marriage years × 12 × 0.33. A 10-year marriage yields 39.6 months — about 3 years 4 months of support.
The monthly payment is rounded to cents first, then multiplied by the duration in months to produce the total obligation.
Length of the marriage. This is the primary driver of duration. Short marriages (under a few years) typically produce brief or no support, while long marriages can produce support lasting many years or even indefinitely in some states.
Income disparity. The larger the gap between the spouses' incomes, the higher the monthly payment under both formulas. If the incomes are close or the recipient earns more, the formulas return $0.00.
Standard of living and contributions. Courts also weigh the lifestyle established during the marriage and non-financial contributions such as raising children or supporting the other spouse's career — factors no simple formula can capture.
Longer marriages mean longer support under the one-third rule — and some states award permanent alimony for marriages of 20+ years.
A wider income gap raises monthly payments. Both modes scale directly with how much the payer out-earns the recipient.
Courts aim to avoid a drastic drop in either spouse's lifestyle, which can push awards above or below formula estimates.
Alimony rules differ by state — some use formulas, others give judges broad discretion. Your state's guidelines always take priority.
Document everything early. Gather pay stubs, tax returns, and bank statements for both spouses before negotiations begin. Accurate income figures are the foundation of any support calculation, and the verified examples above show how sensitive the result is to those inputs.
Negotiate before going to court. Mediation or collaborative divorce often lets both sides agree on an alimony amount and duration that works for their situation, rather than leaving it to a judge's discretion. A negotiated agreement can also include terms a formula would never produce.
Include bonuses, commissions, rental income, and side earnings. Understated income produces misleading estimates and can be challenged in court.
Mediation and settlement typically cost far less than litigation and give you control over the amount, duration, and terms of support.
For divorces finalized after 2018, alimony is neither deductible by the payer nor taxable to the recipient. Factor this into any settlement offer.
State laws, retirement division, and tax rules interact in complex ways. A licensed attorney turns this estimate into a workable strategy.
⚠️ Important Note: This calculator provides estimates for general information only. Actual amounts vary by jurisdiction, provider, and individual circumstances. Consult a qualified professional (attorney, accountant, or licensed advisor) for advice specific to your situation.
Alimony law is highly state-specific, and formula results are starting points — not guarantees. If you are negotiating or litigating support, bring this estimate to a family law attorney along with complete income documentation for both spouses.