Will My Money Last in Retirement? How to Estimate Your Run-Out Date

June 30, 2026 · 7 min read

It's the question behind every retirement plan: will my money actually last?Not "do I have a big number," but "if I stop working and start spending, when — if ever — do I run out?" That date, your run-out date, is the single most useful thing to know about your plan, because everything else (when to claim Social Security, how much you can spend, whether to work one more year) flows from it.

What "running out of money" really means

In retirement, most months your guaranteed income — Social Security, a pension, an annuity — doesn't fully cover your expenses. The gap comes out of savings. As long as your accounts can cover that gap, you're fine. You "run out" the first month the shortfall is bigger than what's left in your accounts. Your run-out date is simply the month that happens — or "never," if your income and savings outlast you.

The six things that decide your run-out date

• Guaranteed income — Social Security, pensions, annuities, and when each starts.
• Spending — your real monthly expenses, including the big lumpy ones (healthcare, a new roof, travel early on).
• Savings — balances across 401(k)/IRA, brokerage, and cash, and the order you draw them down.
• Investment returns — what your accounts earn while you're drawing them down.
• Inflation — quietly raising your expenses every year; healthcare usually faster than the rest.
• Longevity — how long the money has to last, which is genuinely unknowable.

Change any one of these and the run-out date moves, sometimes by years. That's why a single "number you need to retire" is less useful than a projection you can adjust.

Why rules of thumb fall short

You've probably seen shortcuts: "save 25× your expenses," "withdraw 4% a year," "you'll spend 80% of your pre-retirement income." They're fine starting points, but they assume a smooth, average world. Real retirements aren't smooth: Social Security starts at one age and a pension at another, the mortgage gets paid off in year 8, healthcare jumps before Medicare, and markets don't deliver the same return every year. A rule of thumb can't see any of that. A month-by-month projection can.

How to estimate your run-out date

The reliable way is to project your plan month by month. For each month, you:

• add up the income streams that are active that month (grown for cost-of-living),
• subtract your expenses (grown for inflation),
• cover any shortfall from your accounts in a sensible order — cash first, then taxable, then tax-deferred,
• and carry the balances forward, letting them grow.

The first month the accounts can't cover the gap is your run-out date. Doing this by hand in a spreadsheet is possible but tedious — and easy to get wrong once you add a spouse, multiple income start dates, and inflation. A dedicated tool does it in seconds and lets you test changes instantly.

One projection isn't enough: the role of luck

A single projection assumes one fixed return every year. Reality is bumpier, and the orderof good and bad years matters enormously — a market crash in your first few years of retirement does far more damage than the same crash later, because you're selling investments to live on while they're down. This is called sequence-of-returns risk. The way to account for it is to run hundreds of randomized scenarios and ask: in what percentage does the money last? An 85–95% success rate is a much more honest answer than a single line on a chart.

Five ways to push your run-out date later

• Delay Social Security. Waiting from 62 to 70 can raise your benefit by ~70%+ — inflation-adjusted, guaranteed income for life.
• Trim recurring expenses. A few hundred dollars a month, compounded over decades, moves the date years.
• Work part-time for a while. Even modest income early on means you sell fewer investments during the riskiest years.
• Be flexible in down markets. Spending a little less after a bad year is one of the most powerful levers there is.
• Mind the withdrawal order. Drawing accounts in a tax-smart sequence stretches the same balances further.

You don't have to guess at any of this. Enter your numbers, see your run-out date, then try each change and watch it move — that's exactly what Retirement Forecast is built to do.

This article is general education, not financial, investment, or tax advice. Projections are estimates that depend on your inputs and assumptions; consult a qualified professional about your own situation.