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Retirement calculator
Two questions, one model. Tell it what you can save and it returns the monthly pension that buys; tell it the pension you want and it returns the saving that funds it. The chart draws the whole arc — the pot building to your retirement age, then being drawn down to nothing over the years you asked it to cover.
How to use it
- Choose which way round to ask: “I know what I can save” or “I know the pension I want”.
- Set your age now, the age you plan to stop, and how many years of pension the pot has to cover.
- Enter what you have already saved and either your monthly contribution or your target pension.
- Open “Return and inflation” to set a different return for the saving and drawdown phases — a pot being spent is usually invested more cautiously than one being built.
A drawdown is a loan you make to yourself
The two halves of this chart are the same equation pointing in opposite directions. Building the pot is a series of deposits growing at a rate; spending it is a series of withdrawals from a balance that is still growing at a rate — which is arithmetically identical to a repayment loan, where the retiree is the lender and the pot is the borrower. The monthly pension comes out of the same annuity formula that produces a mortgage payment, and that is not a coincidence or a shortcut.
It has one consequence worth internalising. The pension is set so that the pot lands exactly on zero in the final year you asked it to fund. Nothing is left over, and nothing is held back for living longer than planned. Push the payout years out and the monthly figure drops immediately — that trade is the single most important thing this page shows, and it is why the years-to-fund slider deserves more thought than the return one.
Thirty years of inflation is the biggest number here
A projected pension of 3,000 a month in 2056 is not a pension of 3,000. At 2.5% inflation, prices roughly double in twenty-eight years, so that figure buys what about 1,500 buys today — and 2.5% is a benign assumption. Every headline on this page is therefore shown twice: the cash figure, and what it is worth in today’s money at the inflation rate you set. Read the second one.
The same discount applies to the pot itself, which is why the dashed line on the chart sits so far below the bars by the end. A million in forty years is not a million. Any retirement plan that quotes only nominal figures is flattering itself, and most of them do.
What this model deliberately leaves out
Tax is absent entirely, and it is not a rounding error: contributions, growth and withdrawals are each taxed differently depending on the country you live in and the kind of account you hold, and the same gross pot can produce materially different net income under two wrappers. So is any state or public pension, which for many people is the largest single component of retirement income. So is an employer match, which is usually the highest-return money available to anyone and is worth modelling by simply adding it to your monthly contribution.
Charges are missing too — subtract them from the return you enter — and so is sequence-of-returns risk, the fact that a bad few years immediately after you stop working damages a pot far more than the same years a decade earlier, because you are selling units to live on while they are cheap. A steady annual return is the one assumption every simple calculator makes and no portfolio honours. Treat the output as a way to compare scenarios against each other, not as a forecast, and take a real plan to a regulated adviser. This page is an estimate, not financial advice.
Questions
Why is the pension it gives me smaller than the “4% rule” suggests?
Because they answer different questions. The 4% rule is designed to make a pot last indefinitely without being exhausted, leaving the capital broadly intact. This page instead spends the pot down to exactly zero across the number of years you specify, which produces a higher income for a fixed period rather than a lower one forever. Neither is wrong; they are different plans.
How many payout years should I fund?
More than the average life expectancy, because averages are the point at which half of people are still alive. A healthy 65-year-old in a wealthy country has a substantial chance of reaching 90, so funding 25 years from 65 is a reasonable base case and 30 is not pessimistic.
Why set a lower return for the drawdown phase?
Because most people de-risk as they stop earning. A pot you are actively spending cannot ride out a long downturn the way one you are still adding to can, so it is typically shifted towards bonds and cash, which yield less. Leaving both rates the same models someone who stays fully invested through retirement — a legitimate choice, but a different one.
Does it account for tax relief on contributions?
No. In several countries a contribution is topped up by tax relief or made from pre-tax income, which effectively increases what you pay in — where that applies, enter the gross amount that actually reaches the account rather than what leaves your bank.
Is any of this stored?
No. Every figure stays in this browser tab. There is no account, no upload and nothing written down when you close it.
Updated 2026-08-18. Runs fully in your browser — nothing is uploaded.