Morningstar’s 2025 research puts the safe starting withdrawal rate at 3.9%, judged by whether money is still there in 90% of simulated outcomes, not by an average return. That is the question a Monte Carlo test answers for your own numbers, and it is why the answer above is a probability, not a promise.

Source: Morningstar, The State of Retirement Income 2025 · Dec 2025

Social Security’s own planning guidance: about one out of every three 65-year-olds may live until at least age 90. A plan that stops at 85 quietly bets against a third of retirees. The plan you build here runs to 95 by default, and you can push it further.

Source: Social Security Administration, Retirement Information for Medicare Beneficiaries · 2026

Fidelity’s 2025 estimate for a 65-year-old retiring this year: $172,500 in Medicare premiums, deductibles and prescriptions over retirement, and it leaves out long-term care entirely. That is a line item, not a rounding error, so the engine charges Medicare premiums and income-based surcharges year by year instead of a flat guess.

Source: Fidelity Investments, 2025 Retiree Health Care Cost Estimate · Jul 2025

EBRI’s 2025 Retirement Confidence Survey found only 52% of workers have estimated the monthly income they’ll need. The other half are guessing. The three numbers at the top of this page are that first step, and the engine takes it from there.

Source: EBRI/Greenwald Retirement Confidence Survey 2025, Fact Sheet 3