How this calculator works
This is a drawdown model. It starts with your pot and walks forward one month at a time. Each month it grows the balance by your expected return, subtracts what you spend, and adds any ongoing income such as a pension. Once a year it lifts your spending by the inflation rate, because the same lifestyle costs a little more every year. It keeps going until the balance reaches zero, and that point is your run-out date. If your income and returns keep pace with your rising spending, the pot lasts the full 60 years modelled and you’ll see a 40-plus-year result instead.
Four inputs move the answer the most: the size of your pot, your monthly spending, the return you earn, and the inflation rate you assume. Small changes compound, so it’s worth testing a few scenarios rather than trusting a single number.
How long will my savings last in retirement?
The honest answer is that it depends on four levers: the size of your pot, how much you draw each month, the return your savings earn, and how fast inflation lifts your costs. Rather than lean on a single rule of thumb, this drawdown calculator runs your own figures month by month, so you can see the year your savings would run out and test how spending a little less, or earning a little more, moves that date.
The 4% rule explained
The 4% rule is the best-known shortcut for retirement spending. The idea: withdraw 4% of your starting pot in the first year, then adjust that pound amount for inflation each year after. Historically that withdrawal rate let a mixed portfolio last around 30 years. On a £500,000 pot, 4% is £20,000 a year, or roughly £1,667 a month.
Treat it as a starting point, not a promise. It came from historical US market data, assumes a particular mix of shares and bonds, and doesn’t know your retirement will be shorter or longer than average. If you’re retiring early or want more of a safety margin, a lower rate of 3 to 3.5% is more cautious. The calculator above lets you test what any spending level does to your run-out date.
Understanding the inflation presets
Inflation is the input people underestimate most, so this tool gives you three framings rather than one guessed number:
- Low, the central-bank target or long-run average. What inflation looks like in calm years.
- Moderate, closer to the current headline CPI. A sensible middle assumption for planning.
- High (lived), an essentials-weighted rate. Housing, food and energy tend to rise faster than the headline basket, so retirees often feel a higher personal inflation than the published figure.
These are illustrative assumptions, not forecasts. Inflation moves, and it varies by country, so check the current CPI for your region before you rely on any single figure. The region selector sets sensible defaults, but you can always type a custom rate.
Frequently asked questions
How long will my money last?
It depends on four things: how big your pot is, how much you spend each month, what your savings earn while invested, and how fast your spending rises with inflation. This calculator runs a month-by-month simulation, growing the pot by your return, subtracting your spending, adding any pension income, and increasing your spending each year by the inflation rate, until the balance hits zero. The result is the number of years and months your money lasts.
What is the 4% rule?
The 4% rule is a rough guide that says if you withdraw 4% of your starting pot in year one, then adjust that amount for inflation each year, your money should last around 30 years. On a £500,000 pot that's £20,000 a year, or about £1,667 a month. It's a useful starting point, not a guarantee, it was based on historical US market returns and assumes a mixed portfolio. Real returns, spending shocks and a longer retirement can all change the outcome, which is why running your own numbers matters.
How does inflation affect how long my money lasts?
Inflation shortens the runway. As prices rise, the same lifestyle costs more each year, so you draw down faster. A pot that lasts 30 years at 2% inflation might last only 22 to 24 years at 6%. Because essentials like housing, food and energy often rise faster than the headline rate, many retirees feel a higher personal inflation than the published CPI, which is why this tool lets you model a lived, essentials-weighted rate as well as the central-bank target.
Should I include my state pension, super or social security?
Include any ongoing income you'll receive during the years you're modelling, a state pension, age pension, superannuation income stream or social security payment, in the income field, because it directly offsets what you draw from your pot. One caution for Australia: only include super in your savings pot if you can already access it, as it's locked until preservation age (around 60). If a pension only starts later, remember this tool assumes the income runs for the whole period.
How much can I safely withdraw?
A common rule of thumb is around 4% of your pot a year, adjusted for inflation, aimed at making the money last roughly 30 years. If you want it to last longer, or you're retiring early, a lower rate such as 3 to 3.5% is more cautious. The right number depends on your age, health, other income and how much market risk you can stomach. Use this calculator to test different spending levels and see how each one changes the run-out date.
How long will £100,000 last in retirement?
There's no single answer, because it depends on your spending, returns and inflation. As a simple illustration, £100,000 drawn at £1,000 a month is about 8 years of spending before any investment growth or inflation is counted: growth extends that, and inflation shortens it. Enter £100,000 as your pot above, with your own spending and any pension income, and the depletion chart shows a realistic run-out year.
How long will my pension last?
Your pension lasts as long as the pot, your drawdown rate, your investment return and inflation allow. As a rough guide, the 4% rule suggests a £300,000 pension could support about £12,000 a year, rising with inflation, for roughly 30 years, though the state pension or another income on top lets you draw less from the pot and stretch it further. Enter your pension pot as the starting amount, your monthly spending, and any state or workplace pension income, and the calculator shows the year it would run out. Remember this is a pre-tax estimate, so factor in the tax due on drawdowns.
Does this account for tax?
No, this is a pre-tax estimate. It doesn't deduct income tax on withdrawals or pension income, and it doesn't model tax-advantaged wrappers like ISAs, super or retirement accounts. Your real spendable income will be lower once tax is applied, so treat the result as an upper-bound guide. For a figure you can plan around, factor in the tax you'll pay on drawdowns and speak to a qualified adviser.
This calculator is an estimate to help you think, not financial advice. It gives a pre-tax figure and can’t know your personal circumstances. For decisions about your retirement, speak to a qualified financial adviser.
This tool is a guide, not financial advice.
