How Long Will My Retirement Savings Last?

What this retirement savings last calculator actually answers

You give it a starting balance, how much you plan to take out each month, what you expect your investments to earn, and how much you want that withdrawal to grow each year for inflation. It runs the numbers forward, month by month, until the balance hits zero — or until it's clear the balance is actually growing faster than you're drawing it down, in which case your money effectively never runs out under those assumptions.

That's a genuinely different question from "will I have enough to retire," which is a bigger planning exercise involving your full financial picture. This tool answers something narrower and more concrete: given a specific balance and a specific spending pattern, how many years does the math actually support.

How the calculation works

Every month, two things happen to your balance in this model. It grows by your expected annual return, applied monthly. And it shrinks by your withdrawal amount, which itself increases slightly each year to keep pace with inflation, the same way your grocery bill does. The calculator repeats that cycle until the balance reaches zero, then converts the number of months back into years and an age, so the answer means something concrete rather than an abstract number of months.

This is deliberately a simulation rather than a single formula, because a formula that just divides your balance by your withdrawal rate misses the compounding — money that's still invested keeps earning while you're spending down the rest, and that interaction matters over a 20 or 30 year horizon.

The 4% rule, and why it's a starting point, not a guarantee

The 4% figure comes from research — most famously the Trinity Study — that looked back across decades of historical US market returns and asked: what withdrawal rate, adjusted for inflation each year, would have survived a 30-year retirement in the worst historical stretches, not just the average ones. Roughly 4% held up in the great majority of those historical periods.

That's useful as a reference point, not as a number to apply blindly. It was built around a 30-year horizon and a specific mix of stocks and bonds — retire earlier, invest more conservatively, or want more of a safety margin, and a lower rate makes sense. Retire later with a shorter time horizon, or you're comfortable adjusting spending if markets turn rough, and a higher rate can be reasonable too.

Sequence of returns risk

This is the concept that trips up more retirement plans than almost anything else, and it's worth understanding even though this calculator — like most simple tools — assumes a constant annual return for simplicity. Two portfolios can average the exact same return over 20 years and end up in completely different places, purely because of what order the good and bad years arrived in.

A retiree who hits a market downturn in the first few years of retirement is selling investments at depressed prices to cover withdrawals, which locks in losses that a portfolio never fully recovers from — even if the following years are strong. A retiree who hits that same downturn a decade later, after their balance has already grown, weathers it far more comfortably. Same average return, very different outcome, entirely because of timing.

Why inflation changes the answer more than people expect

A fixed $2,500 a month sounds simple, but it doesn't buy the same amount of groceries, insurance or gas in year 20 that it does today. Most realistic retirement plans increase withdrawals over time to preserve actual purchasing power, not just the dollar figure — which is why this calculator lets you build that increase in directly, rather than pretending prices stay flat for three decades.

Even a modest 2.5% inflation adjustment compounds meaningfully over a long retirement. It's a large part of why a withdrawal rate that looks comfortable on paper in year one can become a genuine strain by year fifteen if returns don't keep pace.

How to use this calculator

Enter your current savings balance and your age today. Add the monthly amount you plan to withdraw from that balance specifically — not your total spending, just the piece coming out of savings, since guaranteed income like Social Security is entered separately. Set an expected annual return that reflects your actual investment mix, and an inflation rate for how much you want that withdrawal to grow each year. The result updates as soon as you change any number.

Social Security, pensions and other guaranteed income

Guaranteed income changes this calculation more than almost any other input, because it directly reduces how much your savings actually need to cover. If Social Security or a pension already covers your baseline living costs, your monthly withdrawal from savings might be far smaller than your total monthly spending — and that gap is exactly what extends how long a portfolio lasts.

Use the "other income" field to keep that guaranteed income separate in your own thinking, and make sure the withdrawal figure you enter reflects only what's actually coming out of your investment balance, not your full monthly budget.

Required minimum distributions, briefly

If a meaningful share of your savings sits in a traditional 401(k) or IRA, the IRS requires you to start withdrawing a minimum amount each year once you reach a certain age — currently 73 for most people, based on current law. Those required minimum distributions, or RMDs, don't have to match what you'd otherwise choose to withdraw, and they can push your actual withdrawal rate higher than planned in certain years. This calculator doesn't model RMDs specifically, since account type and tax treatment vary a great deal — worth factoring in separately once you're within a few years of that age.

What actually happens if the money runs out

If a portfolio does deplete, spending typically has to fall back to whatever guaranteed income remains — Social Security, a pension, or both — which for most people is a significant step down from what savings had been supplementing. That's not a reason to panic over a single scenario in a calculator; it's exactly why running the numbers well before retirement, rather than a few years in, gives you room to adjust the plan while adjustments are still easy to make.

Practical adjustments include working a few more years before retiring, trimming the planned withdrawal rate, or reworking the investment mix. Small changes made early tend to matter far more than large changes made late, simply because there's more time for them to compound.

Ways to extend how long your savings last

• Delay retirement, even briefly. Extra working years both grow the balance and shrink the number of years it needs to cover.
• Delay claiming Social Security. Benefits generally increase for each year you wait past your full retirement age, up to 70 — which raises your guaranteed income floor for the rest of your life. The Social Security Administration's own guidance lays out exactly how much waiting adds to your benefit.
• Trim the withdrawal rate. Dropping from 5% to 4% doesn't sound dramatic, but it materially changes how many decades a portfolio can support.
• Stay flexible in down years. Retirees willing to spend a little less during a market downturn, rather than withdrawing a fixed amount regardless, tend to preserve their portfolios noticeably longer.
• Review your investment mix. A portfolio that's too conservative can struggle to keep pace with inflation over a long retirement; one that's too aggressive raises sequence-of-returns risk right when it matters most.

Fixed vs percentage vs guardrail withdrawals

This calculator models a fixed dollar withdrawal that grows with inflation, which is the easiest strategy to picture and plan around — but it's not the only approach retirees use. A percentage-of-balance strategy withdraws a set percentage of whatever the portfolio is worth each year, which automatically reduces spending after a bad market year and increases it after a good one, at the cost of a less predictable income.

A "guardrails" approach sits between the two — you withdraw a fixed inflation-adjusted amount most years, but agree in advance to cut spending if the portfolio falls below a certain threshold, and allow yourself a raise if it grows well beyond expectations. None of these is universally "correct" — they trade off predictability against resilience differently, and the right choice depends on how much year-to-year variation in spending you can genuinely live with.

Healthcare costs — the number people forget

Healthcare tends to be one of the largest and most unpredictable costs in retirement, and it's easy to underestimate when building a simple monthly withdrawal figure. Medicare covers a meaningful share of costs starting at 65, but premiums, supplemental coverage, and out-of-pocket costs for anything beyond routine care can add up well beyond what a flat monthly estimate assumes. It's worth padding your withdrawal figure, or running a separate scenario with a higher amount, specifically to stress-test how a bad health year would affect the numbers above.

Common mistakes when estimating this

• Using today's spending without adjusting for inflation. A flat withdrawal number quietly understates how much you'll actually need in later years.
• Ignoring guaranteed income entirely. Ability to withdraw from savings and total spending need are two different numbers — mixing them up understates how long a portfolio really lasts.
• Assuming a smooth, constant return every year. Real markets don't move in a straight line, and the timing of a downturn matters as much as its size — see sequence of returns risk above.
• Not revisiting the plan. A calculation run once at retirement and never checked again misses genuine chances to course-correct while it's still easy to do so.
• Forgetting healthcare and long-term care costs. These tend to be underestimated more than any other retirement expense category.

When it's worth talking to a professional

A calculator like this one is genuinely useful for building intuition and testing scenarios quickly, but it's not a substitute for a full financial plan — particularly once tax treatment across different account types, Social Security claiming strategy, and estate planning start interacting with each other. A fee-only fiduciary financial planner, someone legally required to act in your interest rather than sell you a product, is worth the conversation once you're within a few years of retirement or the numbers here feel uncomfortably close to the edge — NAPFA's advisor directory is one place to find one.

The bottom line

There's no single number that answers how long retirement savings last for everyone — it genuinely depends on your balance, your withdrawal rate, your returns, and how you handle the inevitable bad years mixed in with the good ones. What a retirement savings last calculator like this one can do is turn that uncertainty into a concrete, adjustable estimate, so you're planning around real numbers instead of a guess.

Run your own figures above, then try a slightly lower withdrawal or a slightly later retirement date and see how much difference it makes. Small adjustments made early tend to move the "how long will my retirement savings last" answer more than most people expect.