Can I Afford to Retire Calculator: Your Odds in 1,000 Futures

According to the EBRI/Greenwald Retirement Confidence Survey 2025, 48% of workers have never estimated how much they'll need each month in retirement. That's about half of everyone saving for retirement, and they're guessing. If you're searching for a can I afford to retire calculator, you're already past that point. Here's the honest answer up front: no calculator can tell you yes or no. A good one tells you your odds, meaning how often your savings last when your plan runs through many possible futures. That's a much more useful thing to know.

This guide covers how that kind of answer works, what a "success rate" means, and which few numbers move it the most.

The short answer: you get a probability

Most basic retirement calculators take your savings, assume one average return, say 6% a year, and draw a smooth line into the future. The line either reaches your target or it doesn't.

Markets don't move in smooth lines, though.

A better question is this: across a wide range of realistic market paths, how often does my money last? Suppose the answer is 900 out of 1,000. That's a 90% success rate. It isn't a guarantee. It's a measure of how robust your plan is.

That's the standard the research uses too. Morningstar's safe withdrawal rate research (more on it below) judges a spending level by whether money is still left in 90% of simulated outcomes. It doesn't judge it by the average return.

How a can I afford to retire calculator should work

Three numbers are enough to start:

1. Your age. This sets how many years your money has to last.
2. What you've saved for retirement. This is the pot you'll draw from.
3. What you spend each month. This is the draw on that pot.

From there, the calculator should do the heavy lifting.

Monte Carlo in plain English

"Monte Carlo simulation" sounds technical. The idea is simple.

Rather than assume one future, the software creates many: 1,000 is common. Each one has its own sequence of good years, bad years and flat years. In some futures, markets boom early. In others, they crash in year two and take a decade to recover. Your savings and spending run through every one of them.

Then you count. In how many of the 1,000 futures did the money last to the end of the plan? That count is your success rate. As Income Laboratory explains, a 90% result means the money lasted in 900 of 1,000 simulated scenarios.

Why averages mislead: sequence-of-returns risk

This is the part most "can I afford it" pages skip, and it's the main reason simulation beats a single projection.

Take two retirees with the same average return over 30 years. One gets the bad years first and the other gets them last. Their results can be very different.

Why? Once you're retired, you're withdrawing money every year. A crash early on means you sell investments while they're down to cover your spending. Those dollars aren't there when markets recover. The same crash 20 years in does much less damage, because the portfolio has already done most of its work.

A single average-return calculator can't see this. A simulation can, because the order of returns is different in each of its 1,000 futures.

What your success rate actually means

A percentage on its own can feel abstract. Here's a plain reading of what different results are telling you:

Two caveats matter here.

First, a "failed" future is usually not literal ruin. Most simulations assume you keep spending the same amount no matter what. Real people adjust. They trim travel after a bad year or put off a big purchase. A future that "fails" in the model often means one where you'd have needed to cut back at some point, not one where you end up with nothing.

Second, 100% isn't the goal. Pushing for certainty usually means working years longer or spending far less than you could. That's a trade-off too. Morningstar uses a 90% threshold for a reason.

These are general ways to read a result. They aren't a recommendation for your situation. What counts as "enough" depends on your other income, your flexibility and how much risk you can live with.

The numbers that move your odds most

If your result surprises you, one of these is usually why.

1. How much you withdraw

Morningstar's research puts the safe starting withdrawal rate at 3.9%. That's the share of your portfolio you can take in year one, then adjust for inflation, with a 90% chance the money lasts over a 30-year retirement. It's up from 3.7% the year before. Portfolios with 30–50% in stocks supported the highest rates. (Source: Morningstar, What's a Safe Retirement Withdrawal Rate for 2026?, based on The State of Retirement Income report, published December 2025.)

That's lower than the well-known "4% rule," and the gap is real money. Morningstar usually updates this figure every December, so check for the latest number.

2. How long your money has to last

The Social Security Administration's planning guidance says about one in three 65-year-olds may live to at least 90. (Source: SSA, Retirement Information for Medicare Beneficiaries, 2026.)

So a plan that stops at 85 is quietly betting you'll be in the other two-thirds. Longer retirements also lower the safe withdrawal rate, because the same savings have to cover more years. This is why we run plans to age 95 by default, and you can push that further.

3. Health care

Fidelity estimates that a 65-year-old retiring in 2025 will need $172,500 for Medicare premiums, deductibles and prescriptions over retirement. That figure leaves out long-term care entirely. (Source: Fidelity Investments, 2025 Retiree Health Care Cost Estimate, July 2025.)

That's a line item, not a rounding error. If your monthly spending figure doesn't account for health care, your success rate will look better than it should.

4. How flexible you are

This is the lever people overlook. Coverage of Morningstar's research reports that flexible spending strategies can lift a sustainable starting withdrawal rate to about 5.7%. Those are strategies where you spend less after bad market years and more after good ones. (Reported by Kiplinger and ThinkAdvisor, December 2025.)

The takeaway: being willing to adjust can be worth as much as years of extra saving.

A quick back-of-envelope check

Before you run a full simulation, you can sanity-check your numbers with the 3.9% figure.

From savings to spending:

• $500,000 × 3.9% = $19,500 a year, about $1,625 a month
• $1,000,000 × 3.9% = $39,000 a year, about $3,250 a month

From spending to savings: take the monthly amount you need from your portfolio (after Social Security or a pension), multiply by 12, and divide by 0.039.

• $3,000 a month → $36,000 a year → roughly $923,000

For a broader benchmark, Fidelity suggests aiming for about 10 times your salary by age 67. That assumes you save around 15% of your income from age 25 and want to keep your pre-retirement lifestyle. (Source: Fidelity, How much do I need to retire?)

These rules of thumb are a starting point. They assume a fixed 30-year retirement, they ignore your health care costs and timing, and they can't show you sequence risk. A simulation can.

What no calculator can tell you

Honesty matters here, so let's be clear about the limits.

• Every model is built on assumptions. That includes expected returns, volatility, inflation and how often crashes happen. Change them and the result changes. Some tools assume market returns follow a neat bell curve, which can understate how often big crashes happen. It's fair to ask any tool, ours included, what it assumes.
• Some "Monte Carlo" calculators don't simulate anything. They look up a published withdrawal-rate table and present it as a simulation. Ask how many scenarios were actually run.
• Life isn't in the model. Divorce, a windfall, caring for a parent, a part-time job you end up enjoying: none of these show up until you add them.
• A probability isn't a promise. A 90% plan can still hit a bad stretch, and a 70% plan can turn out fine. What the number tells you is how much margin you have.

That's why stress-testing is worth doing. Break your plan on purpose, before life does. Try a crash in year one. Add five years of life. Raise health care costs. See which change drops your odds the most. That's the risk to plan around.

Run your own three numbers

The fastest way to answer "can I afford to retire?" is to try it with your own figures.

On the Monte Climb retirement calculator, you enter your age, what you've saved and what you spend each month. We run those numbers through 1,000 simulated futures and show you how many stay funded. It runs in your browser, and nothing is saved until you say so.

If you want to dig further, ask William, our AI planner. Ask him "Am I on track?", "Can I retire at 62?" or "What's a sustainable spend?" Talk to him like you would a friend. If you want to build out the full plan, you can try the Monte Climb planning app for $1 for 7 days.

It's planning software, not advice. But it's a clear, data-backed place to start.

Show my answer →

Frequently asked questions

What does a 90% success rate mean in a retirement calculator?

It means your savings lasted to the end of the plan in 900 of 1,000 simulated market scenarios. It measures how robust your plan is across many possible futures. It is a probability, not a guarantee.

Is the 4% rule still safe?

Morningstar's latest research puts the safe starting withdrawal rate at 3.9% for a 30-year retirement with a 90% chance of success, slightly below 4%. Longer retirements lower that rate, and flexible spending strategies can raise it.

How much do I need to retire?

A quick estimate: multiply the monthly amount you need from savings by 12, then divide by 0.039. For example, $3,000 a month works out to roughly $923,000. Fidelity's benchmark is about 10 times your salary by age 67. A simulation gives a fuller picture because it accounts for market order, longevity and costs.

Why use Monte Carlo instead of an average return?

An average return can't capture sequence-of-returns risk. When bad markets hit early in retirement while you're withdrawing, they do far more damage than the same losses later on. Monte Carlo runs many different market paths, so it shows how often your plan survives a rough start.

How long should a retirement plan run?

The Social Security Administration says about one in three 65-year-olds may live to at least 90. A plan that ends at 85 can understate the risk of running out. Monte Climb runs plans to age 95 by default, and you can extend that.