How it works

How the numbers are made

Your plan runs through 500 simulated market histories. The headline percentage is the share where your money lasts to the planning age. Default results appear immediately; change your inputs to explore your own situation.

Market histories use blocks of real US stock and bond returns after inflation, beginning in 1928. Keeping stretches of years together preserves runs of good and bad markets. Returns are scaled to the published model assumptions; this does not predict future returns.

The assumed real return is 5% before an annual investment fee of 0.25%. Amounts are in today's dollars. A real return is after inflation, and the compounded return can differ from the arithmetic average.

Your income and spending

Enter total yearly spending including health insurance and out-of-pocket costs. Savings fund the years between retirement and the start of Social Security or other fixed income. Social Security rises with inflation; other fixed income does not. Moderate adds household and itemized income details. Advanced also lets you model spending changes and separate healthcare costs.

A Social Security estimate may assume you keep earning until you claim. If you plan to stop working earlier, get an estimate that reflects that earnings stop date. The calculator uses the benefit amount you enter and does not reconstruct your earnings history.

The model does not include long-term care or large one-off medical bills. It does not predict future Social Security policy; Advanced includes a reduced-benefit scenario as a sensitivity test.

Taxes and account assumptions

Federal tax on retirement withdrawals is included. With a single savings total, the model assumes 70% pre-tax, 20% taxable, and 10% Roth. Moderate and Advanced let you itemize your accounts. Your actual account mix and tax situation can change the result.

The model includes tax on assumed taxable-account distributions, early-withdrawal penalties, and required minimum distributions under its account rules. It does not model every access exception, including the Rule of 55. State income tax, ACA premium subsidies, and Medicare income surcharges are excluded.

The tax summary uses a separate average-return path to illustrate costs. It is not the total tax from every simulated market history.

Planning beyond average life expectancy

The planning age uses the Social Security Administration cohort life tables (2024 Trustees Report), following your birth year forward and blending male and female tables by default. Advanced lets you specify a table and adjust the planning assumptions. It plans beyond average life expectancy. The results also compare a shorter and longer life using the same plan.

The chart shows a range across simulated market outcomes. That range does not cover every uncertainty in lifespan, inflation, fees, taxes, benefits, or future returns.