Retirement Withdrawal Calculator and 4% Rule Simulator

What this retirement withdrawal calculator answers

Choose one of three paths: estimate how long a portfolio may last at your chosen starting rate or income, find the income a portfolio may support at a selected confidence target, or estimate the starting portfolio required for desired income. The probability result tests sequence risk; it is not a guarantee or a prediction of future markets.

How to use the result

Start with central assumptions, then compare conservative and poor-first-five-years cases. Focus on the success rate, downside balance, and any suggested spending reduction—not only the median. Include fees and known pensions because they materially change the amount taken from investments. Recheck a pension drawdown plan regularly as spending, markets, and circumstances change.

Exact calculation method and assumptions

1. The first-year spending target is the selected rate times starting portfolio, or the entered/solved income. In inflation-adjusted mode, that nominal target rises once at the start of each later year by annual inflation. In current-portfolio mode, the rate is recalculated from that year’s opening balance and spending may fall.
2. Other income is entered in today’s money, begins at the selected age, and is assumed to rise annually with inflation. It is subtracted from the total spending target; only the remaining amount is requested from the portfolio.
3. Fund and adviser/platform percentages are added. Each year’s fee equals the opening balance times that combined percentage and reduces the money invested.
4. For beginning-of-year timing, fees and the portfolio withdrawal are deducted before that year’s return. For end-of-year timing, fees are deducted, the return is applied, and then the withdrawal is taken.
5. If available assets cannot meet a scheduled portfolio withdrawal, the path fails in that year, the remaining balance is taken, and the balance stops at zero. The displayed depletion age is the median age among failed paths. Monetary outputs are rounded only for display.
6. Nominal investment return is sampled annually from a normal distribution using the expected return and volatility, with losses limited to −95% to prevent a mathematically impossible balance below zero. The tool runs 1,200 reproducible paths. Success means every scheduled withdrawal was met through the full horizon.
7. The central projection applies the expected return every year (except the disclosed stress sequence). Today’s-money values divide nominal amounts by (1 + inflation)^year. Constant average returns do not model volatility and cannot establish a genuinely safe withdrawal rate.

Poor first five years preset: applies −15%, −8%, −2%, +3%, and +4% in years 1–5 to every path, then resumes random returns around 6% with 15% volatility. Conservative uses 4% return/12% volatility; central 6%/15%; optimistic 7.5%/16%. These are illustrations, not forecasts.

Worked £500,000 retirement example

Why return order matters

A loss early in retirement is paired with a withdrawal when the portfolio is already down, leaving less capital for the recovery. Reversing the same series of returns can therefore produce a different ending balance even though the arithmetic average return is identical. Use the “Poor first five years” preset to see this sequence-of-returns risk directly.

Evidence, limitations, and financial trust

The 4% rule traces to William Bengen’s 1994 historical analysis and was developed further by Cooley, Hubbard, and Walz in research commonly called the Trinity Study. That work used historical US stock and bond returns. It may not transfer directly to other countries, portfolios, retirement lengths, fees, valuations, taxes, or future markets. The Financial Conduct Authority also identifies sustainability, investment risk, tax implications, and charges as important drawdown considerations.

• Bengen (1994), “Determining Withdrawal Rates Using Historical Data”
• Cooley, Hubbard & Walz, “Retirement Savings: Choosing a Withdrawal Rate That Is Sustainable”
• Financial Conduct Authority: pensions and retirement-income guidance

Monte Carlo results are model-dependent and do not include tax, changing inflation, return correlations, fat-tailed crashes beyond the optional stress sequence, spending changes, or mortality. A high simulated probability does not make a plan safe or suitable.

Retirement withdrawal calculator FAQs

What is a safe withdrawal rate?

A safe withdrawal rate is a starting level of portfolio withdrawals intended to last for a chosen retirement period. It is not one universal percentage: the horizon, asset mix, fees, inflation, taxes, spending flexibility, and return sequence all matter.

How long will £250,000, £500,000, or £1 million last?

At a 4% starting rate, those portfolios provide £10,000, £20,000, or £40,000 respectively in year one before tax, then rise with inflation in the classic rule. How long each lasts depends on returns, volatility, fees, inflation, other income, and the retirement horizon; use the calculator rather than treating 25 times income as a guarantee.

Is 4% still safe?

Four percent is a historical rule of thumb, not a promise. It was developed from historical US stock and bond data for roughly 30-year retirements, so a different country, valuation, portfolio, fee level, future market, or 40- to 50-year horizon may justify a lower or flexible rate.

Is the 4% rule monthly or annual?

It is an annual starting rule: withdraw 4% of the initial portfolio during year one, commonly paid in monthly instalments, then increase the pound amount with inflation each year. It is not normally recalculated as 4% of the current balance every month.

What changes for a 40- or 50-year retirement?

A longer retirement exposes the portfolio to more withdrawals, inflation, fees, and bad return sequences. Holding everything else constant, the supported starting withdrawal is usually lower for 40 or 50 years than for 30 years.

How do inflation, fees, and tax affect retirement withdrawals?

Inflation raises the nominal cash needed to preserve spending power, and fees reduce the return retained inside the portfolio. Tax reduces spendable income but is not calculated here, so all income and withdrawal results are gross before tax.

How do asset allocation and sequence risk affect withdrawals?

Asset allocation influences both expected return and volatility. Losses early in retirement can be especially damaging because withdrawals leave less capital available for a recovery, even when the long-run average return later matches a smoother scenario.

What is the difference between inflation-adjusted withdrawals and a percentage of the current portfolio?

An inflation-adjusted rule starts with a fixed cash amount and raises it with inflation, creating steadier purchasing power but more depletion risk. A current-portfolio rule recalculates income from the remaining balance, reducing depletion risk but allowing income to fall after losses.