The question that doesn't go away

Once you stop working, the math of money reverses. For decades, you were building — adding to accounts, watching balances grow. In retirement, you're drawing down. And the question that comes with that shift is hard to shake: will it last?

It's worth taking seriously, and it's worth understanding precisely. Not the vague fear of running out, but the actual mechanics — what determines how long your money lasts, and what you have control over.

The three forces working against your balance

A retirement portfolio faces three pressures simultaneously.

Your spending. Every year you withdraw money to live on — and your spending tends to rise with inflation. What costs $50,000 this year costs $51,500 next year at 3% inflation. Every projection needs a built-in spending growth assumption, not a flat number.

Your portfolio's growth. Your accounts continue to earn returns in retirement. That growth offsets some of your withdrawals. But if you're spending more than you're earning, the balance shrinks — and a smaller base generates less growth the following year.

Time. The longer you live, the more years those first two forces interact. A small mismatch between spending and growth compounds over decades. What looks manageable at 65 can accelerate into a real problem by 80.

The calculator models this arithmetic: each year, the portfolio grows, then you subtract spending. If the balance stays above zero, repeat. If it reaches zero, the money ran out at that age.

A worked example from the engine

Here's the arithmetic made concrete.

Suppose you retire at 65 with $800,000, spending $50,000 a year. Your portfolio earns 5% annually. Inflation runs at 3%.

In year one: $800,000 grows to $840,000. You spend $50,000. Ending balance: $790,000.

That first-year loss of $10,000 doesn't look alarming — you're drawing down slowly. But your portfolio only earned $40,000 while you spent $50,000. You're already spending more than you're earning. And the gap widens every year: your spending grows with inflation while the balance that generates returns slowly shrinks.

By age 85 — twenty years later — the money is gone. That's not a worst case. It's the straightforward arithmetic of 5% growth against $50,000 in year-one spending that rises 3% annually.

Now change one variable: spend $30,000 a year instead of $50,000, same everything else. The money outlasts a model that runs to age 105. The spending rate is the dominant lever. Not the return rate. Not which investments you hold. How much you spend each year — and whether that amount is sustainable — is what primarily determines how long the money lasts.

Where withdrawal order enters

Most retirees hold money in several different account types, each taxed differently. The order in which you draw from them shapes your tax bill every year of retirement — and over 25 or 30 years, the cumulative effect can be substantial.

The three main account types:

  • Taxable accounts (regular brokerage accounts): you've already paid income tax on contributions; withdrawals of gains are taxed at capital gains rates, which are often lower than ordinary income rates.
  • Traditional accounts (traditional IRA, 401(k)): contributions were pre-tax; every dollar you withdraw is ordinary income. At age 73, the IRS requires minimum distributions from these accounts regardless of what you want.
  • Roth accounts (Roth IRA, Roth 401(k)): contributions were after-tax; qualified withdrawals are entirely tax-free, and there are no required distributions during your lifetime.

The conventional wisdom — draw from taxable accounts first, then traditional, then Roth — has a simple logic: let the tax-advantaged accounts compound longer. Your Roth earns tax-free returns every year you don't touch it. Every year of untouched Roth growth is a year of genuinely free compounding.

The case for flexibility: managing your bracket

The conventional sequence has a weakness. It tends to leave large traditional-account balances untouched until required minimum distributions force large withdrawals starting at 73. By then, you may have no choice about when or how much income to recognize — and that income may push you into higher tax brackets and trigger higher Medicare premiums just when your spending needs are rising.

A more deliberate approach: watch your marginal tax bracket each year, and be willing to draw from traditional accounts — or convert some to Roth — in years when your income is unusually low.

The gap years between retiring and claiming Social Security are often the most valuable here. Your income may be lower in those years than it will be once Social Security starts and required distributions kick in. That lower income means more room in lower tax brackets — a window for Roth conversions at reduced rates that won't repeat.

This is tax planning, not investment advice. It's about which account to draw from, and when — not what to hold inside those accounts.

Sequence of returns: timing matters more than averages

There's one more concept worth naming: sequence-of-returns risk.

The average return over a 30-year retirement is one number. But the timing of individual years matters far more than the average. If the first five years of retirement bring low or negative returns while you're making regular withdrawals, those withdrawals lock in losses in a way that later strong years can't fully repair.

Here's why: a portfolio that loses 20% at age 67 and then earns above average for the next 20 years ends up worse than one with the same arithmetic average that earned it in a smoother sequence. The early losses reduce the base that future returns compound on — and can't be recovered at the same rate.

The practical implication isn't about how to invest. It's about spending flexibility. Retirees who can reduce discretionary spending in a down year — deferring a major purchase, trimming travel, pulling back on optional expenses — protect their portfolios in a way that mechanical fixed withdrawals don't.

Having accessible funds for near-term expenses — money you don't have to generate by selling long-held assets at bad prices — also provides a buffer against being forced to sell in bad conditions. This is cash-flow planning, not investment strategy: knowing what you need, when, and where it will come from.

The decision: what to do

Model your actual spending. The worked example uses round numbers. Your retirement has real ones. Know what you will actually spend — and which parts are essential versus discretionary. That distinction matters more in down years.

Map your accounts by type. List every account: taxable, traditional, Roth. Know roughly how much is in each. The distribution of your assets across account types determines how much flexibility you have in managing withdrawals.

Plan the conversion window. If you retire before RMDs and Social Security, those lower-income years are an opportunity. Converting some traditional money to Roth at lower rates now can reduce forced taxable distributions later — and meaningfully reduce the tax burden on a surviving spouse who will eventually file alone.

Test your withdrawal rate with real numbers. Use the calculator below to enter your actual balance, spending, and assumptions. See how long the money lasts. Then change one variable at a time: what happens if you spend $5,000 less per year? What if returns average 4% instead of 6%? The sensitivity matters.

Build in some spending flexibility for the first decade. The early years of retirement carry the most sequence-of-returns exposure. Knowing which spending is optional — and being willing to act on that — provides a real form of protection.

Common mistakes

  • Drawing down accounts in whatever order is most convenient. Taking from the most accessible account rather than the most tax-efficient one is one of the easiest avoidable mistakes in retirement planning.
  • Using a flat spending assumption. Spending the same nominal amount every year feels stable; in real terms, it's a gradual reduction in your standard of living as prices rise. Build inflation into every projection.
  • Skipping the conversion window. The low-income years early in retirement — before Social Security and before RMDs — are often the best opportunity for Roth conversions. Waiting until required distributions begin is usually more expensive.
  • Treating the first-year balance as the durable number. After a good first year, the balance may look healthy. The relevant question is the trajectory: what does the math do from here over 20 years?
  • Underestimating the effect of fees. A 1% annual fee on a $700,000 portfolio doesn't cost you $7,000 — it costs you $7,000 in year one, plus everything that money would have earned for the rest of retirement. Compounding makes fees more expensive in retirement than they look.

Run your numbers →

Run your numbers →

Enter your real numbers: starting balance, annual spending, expected growth rate, and inflation assumption. The calculator projects the balance year by year and shows exactly how long the money lasts — and what changes when you adjust each variable.

This is educational content about retirement planning concepts, not personalized financial advice.

Keep learning →

Understanding how long your money lasts sets up the next question: what will the IRS require of it? Starting at age 73, pre-tax accounts come with mandatory withdrawals that arrive on a schedule you don't control — understanding them now gives you years of planning time.