Why This Exists
Most retirement calculators are bad.
Not bad in a “could be improved” way. Bad in a “this will lead you to wrong conclusions about the most important financial question of your life” way.
They assume a flat rate of return — as if the market gives you a steady 7% every year and never has a terrible decade. They ignore taxes, or wave them off with a single “effective rate” input. They treat all your money like one big pile, when in reality your 401(k), your Roth, and your taxable brokerage account all behave completely differently. They don’t model RMDs. They don’t model inflation beyond a single static number. They don’t test your plan against actual history.
And then they hand you a green checkmark and say “you’re on track.”
That’s not planning. That’s guessing with a nicer interface.
This calculator was built to fix that.
What It Actually Does
This isn’t a calculator in the traditional sense. It’s a simulation engine.
It takes your real numbers — your spending, your savings, your account types, your expected retirement age — and runs them through 99 years of actual U.S. market history. The Great Depression, the stagflation of the 1970s, the dot-com crash, 2008, COVID, and everything in between.
Then it does it again, thousands of times, using Monte Carlo simulations that shuffle those historical years into randomized sequences. Different orders, different outcomes, different stress tests on your plan.
It models your taxes using real federal brackets, standard deductions, and capital gains treatment. It handles Required Minimum Distributions automatically. It separates your money into taxable, traditional, and Roth buckets and lets you choose your withdrawal sequence.
When it gives you a success rate, that number means something. It’s not “you’ll probably be fine.” It’s “out of thousands of simulated retirements using real historical conditions, here’s how often your money lasted.”
What It Doesn’t Do
It doesn’t store your data. Nothing you enter is saved, tracked, or sent anywhere. Close the tab and it’s gone.
It doesn’t sell you anything. There are no premium tiers, no upsells, no affiliate links to financial products, and no “talk to an advisor” pop-ups.It doesn’t give you financial advice. It gives you math. Good math, based on real data, but math — not a recommendation. What you do with the results is up to you.
Who Should Use It
Anyone who wants a straight answer to the question: Can I retire?
Whether you’re five years out and want to pressure-test your plan, or twenty years out and want to understand what you’re building toward, or already retired and want to see how your withdrawal strategy holds up — this tool was built for people who want real answers, not reassuring ones.
If you’ve never thought about retirement planning before, start with Part 1 of the blog series: Know Your Real Spending. It’ll walk you through the single most important input the calculator needs.
If you want to understand the methodology in detail, read How It Works.
If you just want to run your numbers, go to the calculator.
Disclaimer
This tool is for educational and informational purposes only. It is not financial advice. It does not replace a qualified financial advisor, tax professional, or estate planner.
The simulations are based on historical data and statistical modeling. Past performance does not guarantee future results. Markets can and will do things they have never done before.
No personal data is collected, stored, or transmitted. Everything runs in your browser.
Use this tool to inform your thinking, not to make decisions in isolation.