Portfolio Drawdown Calculator
How long savings last at a given spend rate.
Calculate how long a portfolio will last at a specified annual withdrawal rate and expected return. Enter portfolio value to see years the portfolio sustains.
What this tool does
This calculator estimates how many years a portfolio lasts given a starting balance, a fixed annual withdrawal amount, and an expected annual return rate. The result shows the time horizon before the portfolio is fully depleted, assuming withdrawals occur at the end of each year and returns compound annually. The calculation is most sensitive to the initial portfolio value and the annual withdrawal amount—larger withdrawals or smaller starting balances shorten the timeline significantly. A typical use case might involve modelling a savings drawdown over retirement or during a career break. The calculator assumes constant real withdrawals, a steady return rate, and no additional contributions or unexpected expenses. Results are for educational illustration and do not account for inflation adjustments, tax implications, or market volatility.
Enter Values
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Formula Used
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Disclaimer
Results are estimates for educational purposes only. They do not constitute financial advice. Consult a qualified professional before making financial decisions.
500,000 portfolio with 30,000/year withdrawal at 5% return lasts 37 years. At 6% return, it can last indefinitely. At 4% return, about 23 years. The gap between 4% and 6% is decades — return assumptions matter enormously for retirement sustainability.
Quick example
With portfolio value of 500,000 and annual withdrawal of 30,000 (plus expected return of 5%), the result is 37.0 years. Change any figure and watch the output shift — it's often more useful to see the pattern than to memorise the formula.
Which inputs matter most
You enter Portfolio Value, Annual Withdrawal, and Expected Return. Not every input has equal weight. Adjusting one input at a time toward extreme values shows which ones move the result most.
What's happening under the hood
Solve for n when portfolio equals zero after n annual withdrawals compounding at return rate. Annual compounding, withdrawals at year end. The formula is listed in full below. If the number looks off, you can retrace the calculation by hand — that's the point of showing the working.
How to use this beyond the first run
Re-run the calculation once a year. Life changes — pay rises, new expenses, interest-rate shifts — and the figure that looked right 12 months ago often isn't today. Annual recalibration keeps the plan honest.
What this doesn't capture
The calculation assumes a steady savings rate and a stable interest rate. Real saving journeys include emergencies, windfalls, and rate changes — especially in easy-access products. The figure is a direction of travel, not a guarantee.
Where to go next
This calculation rarely sits alone in a planning exercise. If you're running these numbers, you'll probably also want the safe withdrawal rate calculator, the maximum savings rate calculator, and the pension drawdown sustainability calculator — each one answers a different question in the same territory. Treating them as a set rather than in isolation usually produces a more honest picture.
A portfolio of £500,000 with £30,000 annual withdrawals at 5 return lasts approximately 37.0 years years.
Inputs
This example uses typical values for illustration. Adjust the inputs above to match a specific situation and see how the result changes.
Sources & Methodology
Methodology
This calculator computes how many years a portfolio sustains a given annual withdrawal amount. It solves for the number of periods (n) at which portfolio value reaches zero, using the standard drawdown formula that accounts for both investment returns and regular withdrawals. The model assumes a constant annual return rate applied to the remaining balance, with withdrawals occurring at the end of each year. It treats returns as compounding annually and does not account for fees, taxes, inflation adjustment of withdrawals, market volatility, or variation in actual returns over time. The calculation also assumes withdrawals continue at a fixed amount regardless of market performance or portfolio balance.
References
Frequently Asked Questions
Is this the 4% rule?
Return assumption sensitivity?
Sequence of returns risk?
What if withdrawal is flexible?
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