Safe Withdrawal Rate Explorer

The formula

withdrawal rate = annual withdrawal ÷ portfolio value × 100
band            = the published rate closest to your withdrawal rate
success rate    = table[stock and bond mix][horizon][band]

There is no simulation on this page. Your two dollar figures produce one percentage, that percentage is matched to the nearest rate the published table has a column for, and the figure in that cell is what you see.

What the success rate actually measures

The study took every rolling period of a given length in its data, for example every 30-year stretch starting in 1926, 1927, 1928 and so on. For each one it applied the withdrawal rate to a starting portfolio, raised the dollar amount every year with actual inflation, and checked whether anything was left at the end. The success rate is the share of those periods that ended with a positive balance.

So a 95% success rate means: in 95 out of every 100 historical stretches, the portfolio was not empty at the end of the period. It says nothing about how close the other 5 came, how much was left over in the ones that worked, or how uncomfortable the ride was.

What it does not mean

• It is not a 95% chance. A historical success rate is a count of what already happened, not a probability of what will happen. A 30-year period starting in 1950 and one starting in 1951 share 29 of the same years, so these are heavily overlapping views of one stretch of history, not independent trials.
• The starting point matters enormously. Where valuations and interest rates sit on the day you begin is one of the largest drivers of the outcome, and it is exactly the thing an average across all start years hides. Two people using the same rate in different years are not running the same experiment.
• It is not a Monte Carlo simulation. Nothing here draws random returns or models a distribution. It is one historical record, counted.
• The author of the source study has said as much. Wade D. Pfau, Ph.D., CFA has written repeatedly that the historical success rates from this line of research are widely misinterpreted, in particular that people read a backtest as a probability. Reading these figures as odds is the mistake the research itself warns about.

Why your rate is rounded to a published band

The table has a column for whole-number withdrawal rates only. A 4.3% rate is looked up in the 4% column, and the page tells you that on screen every time rather than quietly presenting the 4% figure as yours. Only a rate that lands on a published band exactly is described as an exact match; anything else says which band it was read from. When a rate falls exactly halfway between two columns, we use the higher one, which is always the more cautious of the two. We do not interpolate between columns, because the space between two published figures is not itself research.

If your rate is below the lowest published band or above the highest, the page says the rate is outside the published range and shows the nearest band as the closest available reading. That is a signpost, not an answer for your number.

What the table assumes

• A fixed, inflation-adjusted withdrawal. The first-year amount rises with inflation every year afterwards and never responds to what markets did. Real people cut back after a bad year, and that flexibility, which is not modelled here, changes outcomes a great deal.
• Two asset classes. Large US stocks and intermediate-term government bonds, rebalanced to the stated mix. No international holdings, property, cash buffer, or annuity.
• No taxes and no fees. Every figure is gross. Fund costs, advice fees, and tax on withdrawals all come out of the same portfolio and are not deducted anywhere in the table.
• Nothing but the portfolio. Social Security, a pension, part-time income, and any inheritance are all absent. Each one of them reduces what the portfolio has to carry.
• One country, one century. The record is US markets over a stretch in which US stocks did unusually well by world standards. It is a sample of one history, not the range of futures.

How to use it anyway

The honest use of this table is comparative rather than predictive. It is good for seeing that 5% has fared very differently from 4%, that a longer horizon is a materially harder problem, and that a bond-heavy mix has held up poorly at higher withdrawal rates. Those relationships are robust. The exact percentage in any one cell is not a number to plan a life around on its own.

Shared assumptions

• Returns are real, not nominal. Every return figure on this page is already inflation-adjusted, so all dollar amounts are in today's money. There is no separate inflation input to set.
• Returns are smooth. The same return is applied every year. Real markets are not smooth, and the order in which good and bad years arrive changes outcomes materially.
• No taxes, fees, or lumpy spending. Investment fees, taxes on withdrawals, one-off costs, and changes in your spending over time are not modelled.
• Nothing leaves your browser. The whole calculation runs client-side. We do not receive, log, or store anything you type.