Safe Withdrawal Rate Calculator
See how often a withdrawal rate actually survives, instead of taking the 4% rule as a flat answer. Enter your portfolio, how long retirement needs to last, and a withdrawal rate, and this runs it against hundreds of simulated markets to show a real success rate.
Initial withdrawal rate
4.0%Withdrawn as a fixed dollar amount, adjusted for inflation every year after that, same constant-dollar approach as the original 4% rule. It doesn't flex with the market.
Starting portfolio
$1,500,000Retirement length
30 yearsA 30-year retirement is what the original 4% rule was calibrated on. Retiring earlier means a longer stretch the same withdrawal rate has to survive.
Assumed average annual return
A single blended rate, with volatility that scales alongside it, not a real stock/bond split. More aggressive means a higher average return and bigger year-to-year swings, both.
This models portfolio withdrawals only, no Social Security, pension, or other income, no taxes, and a single flat volatility per return tier. ThunderHarbor's full Risk Analysis runs 1,000 simulations against your real accounts, taxes, and guaranteed income, with a choice of withdrawal strategies including guardrails that flex with the market instead of a fixed dollar amount.
What a safe withdrawal rate actually means
A safe withdrawal rate is the percentage of your starting portfolio you withdraw in year one of retirement, then adjust for inflation every year after, that has a high chance of lasting as long as you need it to. The famous version is the 4% rule, which came out of research on 30-year retirements using historical U.S. market data. It was never meant to be a fixed law that applies to every retirement length or every portfolio mix.
A longer retirement needs a lower rate to survive the same range of outcomes. A more conservative portfolio has less growth to outrun inflation-adjusted withdrawals over decades, and a more aggressive one has to survive bigger swings along the way. There isn't one number that's simply "safe," it's a probability that shifts with every input.
Why this tool shows a percentage, not a verdict
This calculator runs your withdrawal rate against hundreds of randomized market sequences, each one a different order of good and bad years built from the same average return and typical volatility you selected. The percentage shown is the share of those sequences where the money lasted the full retirement length without running out.
A rate that survives 95% of sequences is a very different situation than one that survives 60%, even if both are technically "under 4%." Treating a withdrawal rate as a single pass or fail hides that difference. The honest answer is always a range of outcomes, not one number.
Frequently asked questions
What is a safe withdrawal rate?
The percentage of your portfolio you withdraw in the first year of retirement, adjusted for inflation every year after, that has a high probability of lasting your full retirement without running out.
Is the 4% rule still accurate?
It has held up reasonably well for 30-year retirements historically, but it was never a universal law. Retirement length, portfolio mix, and the specific decade you retire into all shift the rate that actually holds up.
Why does this calculator show a percentage instead of a single answer?
A withdrawal rate is never simply safe or unsafe, it survives some market sequences and fails others. This tool reports what share of simulated sequences your money actually lasted through.
Does this calculator account for taxes or Social Security?
No. This is a simplified, portfolio-only estimate. It does not account for taxes, other income, or a real stock and bond allocation.