A withdrawal-rate rule gives you one number for every retirement, good markets and bad. Harbor runs your actual plan through a thousand simulated market histories — with your taxes, your Social Security, and your spending — and tells you the odds.
A flat percentage is calibrated to one bad stretch of history and stops there. Six things a rule of thumb never prices — this one does.
The same average return can wipe out a plan or leave it thriving, depending only on whether the bad years land early. A single average-return projection can't see that — a simulation can.
Ordinary income tax, required minimum distributions, and the taxable share of Social Security are computed year by year inside each of the thousand simulated paths, not estimated once and applied flat.
We draw from your actual IRA, brokerage, and cash balances in the order you specify — not a single blended pot — so the drawdown sequence you'd really follow is the one being tested.
Not a single number held flat for thirty years. We model the spending you actually plan to do, and show what a shortfall in a bad market would mean for it.
"90% success" hides where the other 10% falls — Harbor shows the worst-case paths, not just the average one, so you can see how close a bad run comes to the edge.
Rather than a pass/fail on one assumed rate, we solve for the spending level that hits your target odds of success — a safe-spend figure built for your plan, not a textbook one.
Your accounts, your spending, your Social Security and pension income. Nothing you don't need.
How long the money needs to last, and how much market volatility you want tested against.
Your success rate, your safe spending number, and how the plan performs in a bad-market run.
Year by year: what you'd draw, what you'd owe, and what's left — then print it.
The five questions the tool is built to answer — spelled out here for search engines and for you.
Harbor runs your plan against a thousand different simulated market histories, each built by resampling real historical return and inflation data. A 90% success rate means your money lasted the full retirement horizon in 900 of those 1,000 runs — it is a probability, not a promise.
No. The 4% rule is a single fixed withdrawal rate calibrated to the worst historical stretch on record. Harbor instead simulates your actual accounts, spending, taxes, and Social Security together and reports a safe spending number and a success rate for your specific plan, which is usually a more useful (and often higher) number than the flat rule.
Harbor resamples blocks of real historical annual returns and inflation together, so a simulated run keeps the autocorrelation and the return-inflation relationship that a random, independent draw would erase. It is not a single average return projected in a straight line.
Yes. Every simulated year runs through the same tax engine behind Harbor's Roth and Social Security calculators — ordinary income, RMDs, and the taxable share of Social Security are computed year by year inside each of the thousand runs, not bolted on afterward.
Most calculators assume one smooth market return for every year of retirement. Harbor asks what happens if the bad years land early, prices the odds of running short, and shows a safe spending level — not just whether the average case is fine.
The drawdown decision runs on the same whole-portfolio engine behind Harbor's Roth and Social Security calculators — your accounts, your spending, your taxes, all at once. Free, and your numbers never leave your device.
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