What this result means
Money Longevity answers one decision question: if you spend a set amount each year in today’s dollars, how old will you be when the portfolio runs out under the returns and inflation you entered? The headline age is an estimate from those assumptions — not a forecast of markets, taxes, or lifespan.
That is different from asking “how much can I spend?” (Spending Capacity) or “how often does this plan survive random markets?” (Monte Carlo). Longevity holds spending fixed and solves for time. Spending Capacity holds the planning horizon fixed and solves for spending. Keep those intents separate so you do not mix a depletion age with a sustainable-spend estimate.
If outside income covers part of spending, the portfolio only funds the gap. That often extends longevity more than bumping the assumed return by a fraction of a percent — which is why income fields matter as much as the portfolio total on this page.
What makes retirement savings last longer?
- Spending: Lower draws stretch the same portfolio further; small permanent cuts compound over decades.
- Outside income: Social Security, pensions, or part-time work shrink the portfolio draw.
- Retirement age: Working longer can grow the balance and shorten the draw period.
- Investment return: Higher long-run real returns help, but they are uncertain and should not be treated as a guarantee.
- Inflation: Higher inflation raises the dollars needed to keep the same lifestyle when spending is held in today’s dollars.
How the calculation works
This page uses the same simplified Money Longevity solver as the Projections tools in a free account: a combined portfolio, constant real spending, optional flat retirement income, and a monthly draw loop that continues until the balance hits the floor or the horizon exceeds about 120 years of age. It is intentionally not the full year-by-year baseline engine with per-account withdrawal order and RMDs. See Money Longevity methodology.
If you are not yet retired, optional contribution years grow the portfolio to retirement age first, then longevity runs from retirement. That pre-retirement growth is a shortcut — not a full contribution and tax model — so treat it as directional until you enter real accounts in a free plan.
Example: reading a depletion age
Suppose you start retired with $1.25 million, spend $70,000 per year in today’s dollars, and receive $30,000 of outside income. The engine draws about $40,000 from the portfolio in year one (rising with inflation if you keep real spending constant). Under a steady real return, the result might say the portfolio lasts to approximately age 94 — or beyond age 120 if the draw is low enough relative to return. Change spending by $5,000 or income by $5,000 and the age often moves more than changing the return by half a percentage point. That sensitivity is the point of the tool: see which levers matter for your numbers before you stress-test markets.
How this page differs from our other free tools
- How much can I spend? — flips the question: fixed horizon, solve for spending.
- Monte Carlo — keeps a household plan and varies markets randomly (100 free paths).
- Historical — replays published past market sequences instead of random draws.
- 2-Minute Stress Test — broad baseline + Monte Carlo + historical in one pass.
Important limitations
This calculation uses a simplified combined portfolio. Your full Retirement Planning Center plan models individual Roth, traditional and taxable accounts, RMDs, withdrawal sequencing and year-by-year cash flow. Markets do not deliver a constant real return. Taxes, healthcare shocks, and claiming choices are out of scope here. Educational what-if math only — not advice.
Explore a finished household example in Jim & Susan’s sample plan, or create a free account to replace these shortcuts with your own accounts and assumptions.