What Is the Best Free Monte Carlo Retirement Simulator?

3.9%. That is the starting withdrawal rate Morningstar found survives 90% of simulated futures over a 30-year retirement. The way it's judged matters. It isn't based on an average return. It's based on how often the money is still there at the end. That is the question a Monte Carlo simulator answers for your own numbers, which is why so many people search for the best free Monte Carlo retirement simulator. (Source: Morningstar, The State of Retirement Income 2025, Dec 2025.)

The short answer: there is no single winner. Each tool is good at one thing, and each free version comes with a catch. Below we match tools to needs, explain what the result means, and give you the checks to run before you trust any of them.

A disclosure first. We build retirement planning software, so we have a stake in this. To stay honest, we only cite what other reviewers have published, and we point out where each tool falls short, including ours.

The short answer: pick by what you need

• You want a pure historical stress test with no setup: FIRECalc. It tests your plan against every rolling historical period since 1871, and it's free (CoastIQ).
• You want to experiment with withdrawal rules: cFIREsim. It adds a parametric mode and flexible withdrawal rules such as Guyton-Klinger and VPW.
• You want your real accounts pulled in automatically: Empower. Rob Berger names it the best free calculator. It runs a Monte Carlo simulation once you link your accounts (Rob Berger).
• You want a fast first read without linking anything: a three-number calculator, like the one on our homepage. Age, savings, monthly spending. One success rate back.

What is the best free Monte Carlo retirement simulator for you? A quick comparison

Prices below are as reported by the reviewers cited. They don't always agree with each other, so check them before you sign up.

One more caution. Two of the most visible comparison pages are written by tool makers who rank themselves first. That doesn't make them wrong. It does mean you should read them the way you'd read ours: as a starting point, not a verdict.

What Monte Carlo actually does, in plain English

A basic calculator picks one return, often a steady 7% a year, and draws a smooth line. Real markets don't move that way.

A Monte Carlo simulator runs your plan through hundreds or thousands of possible futures. Some have strong markets early. Some open with a crash. Some have high inflation. Then it counts how many of those futures leave you with money at the end.

That matters because of sequence-of-returns risk: the danger of bad markets in the first years of retirement, when you're withdrawing and can't wait for a recovery. Two retirees with the same average return can end up in very different places depending on the order those returns arrive in. A single-line projection can't show you that. A simulation can.

RetirePro claims that most free calculators use a fixed 7% return and ignore taxes, and that this can shift a retirement estimate by "$200,000 or more" (RetirePro). It doesn't show its method, so treat that as one vendor's claim. The direction is the useful part. Fixed-return math hides risk.

Historical vs. parametric

• Historical tools replay actual past market periods. They're grounded in real data, but they can only test sequences that already happened.
• Parametric (random-scenario) tools generate futures from assumed returns and volatility. They can produce scenarios history never did, but they're only as good as those assumptions.

Neither is wrong. Some tools let you run both and compare.

How to read a success rate

This is the part most comparison pages skip.

A 90% success rate means your money lasted in 9 of every 10 simulated futures. Morningstar's 3.9% figure uses that same 90% standard. It does not mean you have a 10% chance of going broke tomorrow.

Keep three things in mind:

1. Failure has a size and a date. Running short by a small amount at 94 is very different from running out at 75. A single percentage doesn't tell you which one you're looking at.
2. The result depends on the assumptions. Change the expected return or volatility and the number moves. Small tweaks can shift it noticeably.
3. You aren't a robot. Most simulations assume you keep spending the same amount no matter what. In real life, people tend to trim spending after a bad year, and that flexibility can help.

There is a fair critique here. A Seeking Alpha post quotes the view that Monte Carlo amounts to "wild guesses based on precise mathematical calculations." The fix isn't to skip simulation. It's to treat the output as a probability, not a promise, and to rerun it as life changes.

Five checks before you trust any simulator

1. How long does the plan run?

About one in three 65-year-olds may live to at least 90, according to Social Security's planning guidance. A plan that stops at 85 quietly bets against a third of retirees. Check the end age and push it later. (Source: Social Security Administration, Retirement Information for Medicare Beneficiaries, 2026.)

2. Does it account for health care?

Fidelity estimates a 65-year-old retiring in 2025 will spend $172,500 on Medicare premiums, deductibles and prescriptions over retirement. That figure leaves out long-term care entirely. If a tool treats health care as part of a flat spending number, that's worth knowing. (Source: Fidelity Investments, 2025 Retiree Health Care Cost Estimate, Jul 2025.)

3. How does it handle taxes?

CoastIQ reports that Empower and Fidelity use a flat effective tax rate. That's simpler than modeling tax brackets year by year. It's fine for a first pass. It's less useful if you're weighing Roth conversions or required minimum distributions.

4. What does "free" cost you?

Sometimes the price is a paid upgrade. Sometimes it's linking your accounts. Decide which trade-off you're comfortable with. If privacy matters to you, look for tools that work without a login or account connection.

5. Can you see the assumptions?

On a Blind thread, users complain about "black box" assumptions in retirement tools. A good simulator tells you what returns, inflation and spending rules it uses. If you can't find them, be cautious about the result.

Which tool suits whom?

• Planning early retirement (FIRE): FIRECalc, cFIREsim or SorryClub. These are built for long horizons and flexible withdrawal rules.
• Already investing through linked accounts: Empower, if you're comfortable connecting them.
• Want detailed scenario planning and willing to pay: Boldin or ProjectionLab.
• Approaching retirement and want a quick, honest read first: start with three numbers, then go deeper if the answer surprises you.

One gap remains across nearly all of these tools. They're built around US rules. If you live elsewhere, read the results with that in mind.

Where Monte Climb fits

We built Monte Climb for that last group. It takes three numbers: your age, your retirement savings and your monthly spending. It runs them through 1,000 simulated futures and returns one success rate. The calculator runs in your browser, and nothing is saved until you say so.

The plan you build here runs to age 95 by default, and you can extend it. The engine charges Medicare premiums and income-based surcharges year by year instead of a flat guess. If you want to dig into the result, you can ask William, our AI planner, questions like "Am I on track?", "Can I retire at 62?" or "What's a sustainable spend?"

To be clear about limits: we run 1,000 futures, not 10,000. And this is planning software, not advice. The full app is a 7-day trial for $1.

Run your own numbers

EBRI's 2025 Retirement Confidence Survey found that only 52% of workers have estimated the monthly income they'll need in retirement. The other 48% are guessing. (Source: EBRI/Greenwald Retirement Confidence Survey 2025, Fact Sheet 3.)

Whichever simulator you choose, the first step is the same. Put in your real numbers and see how the odds look.

Three numbers. One clear answer. Show my answer.

Frequently asked questions

Is there a truly free Monte Carlo retirement calculator?

Yes. FIRECalc is free and tests your plan against every rolling historical period since 1871. Empower offers a free Monte Carlo tool, but it pulls in your data through linked accounts. Boldin has a free version, with deeper features in its paid tier.

What is a good success rate in a Monte Carlo retirement simulation?

There's no universal cutoff, but 90% is a common benchmark. Morningstar's 2025 safe withdrawal research judged plans by whether money remained in 90% of simulated outcomes. Treat any success rate as a probability, not a guarantee, and look at how and when the failing scenarios fall short.

What's the difference between historical and Monte Carlo simulation?

Historical simulation replays real past market periods, so it can only test sequences that already happened. Parametric Monte Carlo generates random futures from assumed returns and volatility, so it can explore scenarios history never produced but depends on those assumptions. Some tools, such as ProjectionLab and cFIREsim, offer both.

Do I need to link my bank accounts to use a retirement simulator?

Not always. Some tools, such as Empower, pull in data once you link accounts. Others ask you to enter the numbers yourself. Monte Climb's homepage calculator takes three numbers, runs in your browser, and saves nothing until you say so.

How many simulations does a Monte Carlo retirement calculator need?

Tools vary. Monte Climb runs 1,000 simulated futures, and SorryClub runs 10,000. More runs smooth out the result, but your assumptions about returns, inflation, spending and how long you'll live usually matter more than the run count.