How we make our numbers

Every calculator on this site runs on published government formulas, not on our opinions. This page lists the formulas, the assumptions, and where each number comes from, so you (or your advisor, or your lawyer) can check our work. When something varies by state or by judge, we show a range and say so. We never present a range as a promise.

Social Security estimator

• Benefit formula: 2026 bend points of $1,286 and $7,749 with the 90% / 32% / 15% brackets, from SSA's published table. Earnings above the 2026 taxable maximum of $184,500 (SSA) don't count toward benefits.
• Ex-spouse benefit: up to 50% of the worker's full-retirement-age amount, reduced for early claiming by 25/36 of 1% per month for the first 36 months and 5/12 of 1% per month beyond, exactly as published by SSA's actuaries. At 62 with a full retirement age of 67, that works out to 32.5% of his amount.
• Own-benefit reductions and delayed credits: 5/9 of 1% per early month (first 36), 5/12 of 1% beyond; delayed credits of 2/3 of 1% per month after full retirement age, through 70.
• We assume full retirement age is 67, which is true for everyone born in 1960 or later, meaning every reader aged 40 to 60 in 2026.
• When you enter a typical income instead of a benefit figure, we approximate the average indexed monthly earnings as that income divided by 12, capped at the taxable maximum. This "steady career" approximation is close for people whose earnings were fairly stable and less accurate for very uneven careers. That's why we show results as estimates, and why your own Social Security statement beats any calculator, ours included.

Marital share estimator

• 401(k) and IRA accounts use the subtraction method: today's balance minus the balance on the wedding date. States treat growth on the premarital portion differently, so we flag it rather than pretending one rule fits all.
• Pensions use the coverture (time-rule) fraction: months married during plan participation divided by total participation months.
• Division of the marital portion: community property states start from 50/50; equitable distribution states aim for "fair, not necessarily equal," so we show a 40% to 60% band, never a point estimate.
• QDRO flag: employer plans governed by ERISA (401(k), 403(b), private pensions) require a qualified domestic relations order to divide; IRAs divide through the divorce decree instead, per IRS guidance.

House vs. 401(k) comparison

• Traditional 401(k) dollars are compared after your marginal tax rate, because withdrawals are taxed as ordinary income.
• House equity is compared after assumed selling costs of 7% of the home value (adjustable), and we flag when a projected gain exceeds the $250,000 single-filer exclusion on a primary home under IRS Topic 701.

Retirement runway

• A month-by-month simulation in today's dollars using a real (after inflation) return, default 3% per year, adjustable. Income streams (Social Security, pension, support, work) start and stop at the ages you set. We simulate to age 95 and also compute the spending level that lasts exactly to 95.

What we don't do

We don't predict what a judge will decide, we don't calculate spousal or child support (state formulas vary too much to estimate honestly), and we don't give legal or personalized financial advice. Our calculators organize your numbers so that the expensive hours you may buy later are spent on judgment, not arithmetic.

Found an error? We want to know: every page shows its last update date, and we recheck sources when the government publishes new figures each year.