Retirement Calculator: How Long Will Your Money Last?

It projects how your retirement savings grow during the saving phase and how the balance changes once you begin withdrawing in retirement. The saving phase estimates your balance at retirement from current savings, monthly contributions and expected return. The spending phase then models monthly withdrawals, increased for inflation each year, to show whether the money lasts to your plan age, when it may run out, and how much extra you would need to save each month to close any gap. With the default inputs, starting at $50,000 and adding $500 a month at a 6% return before retirement and 2.5% inflation, the projected balance at retirement is about $882,847, equal to roughly $400,610 in today's money. This projection assumes the return, inflation and contribution amounts you enter stay constant every year; if actual inflation runs above 2.5%, monthly withdrawals grow faster than assumed and the pot can run out several years earlier than shown.

The inflation-adjusted balance is the nominal balance divided by the cumulative inflation factor, expressing your future pot in today's purchasing power. With the default inputs, $50,000 start, $500 per month, 6% return and 2.5% inflation over 32 years, the projected nominal balance at retirement is about $882,847, but the inflation-adjusted value is approximately $400,610. The gap between nominal and real widens every year because money saved today buys less when withdrawn decades later. This gap is driven by the cumulative inflation factor, which compounds to roughly 2.2 over the 32-year saving period at 2.5% inflation, meaning every nominal dollar in the projection is worth less than half that in today's terms by the time you retire. A lower assumed inflation rate, such as 2%, shrinks that factor and narrows the gap between nominal and real balances, while a higher rate widens it further and makes the inflation-adjusted figure the more reliable one to plan around.

The target monthly income is your desired retirement spending expressed in today's money, not in future inflated prices. If you enter $2,500, the calculator automatically increases that amount each year by the inflation rate so your spending goal keeps pace with rising prices throughout retirement. This means the pot must be large enough not just to pay $2,500 at the start of retirement, but to fund increasingly larger nominal withdrawals over 28 or more years. At 2.5% inflation, that $2,500 target grows to about $5,509 a month in nominal terms by the time you retire at 67, after 32 years, and to about $10,999 by age 95, which is why the pot needs to fund an increasing withdrawal each year rather than a flat one. If you set the target lower than your real spending needs, for example by ignoring rising healthcare costs, the projection will understate how much you actually need saved by retirement.

The plan age is the age your retirement pot should last until. With retirement at 67 and plan age 95, the calculator models 28 years of inflation-adjusted withdrawals from the pot. Setting a higher plan age, for example 100, increases the required balance at retirement because the pot must fund more years of spending at a growing withdrawal amount.

The return during retirement is the assumed annual growth on the money that remains invested after you stop working. It is kept separate from the pre-retirement return because many people shift to a more conservative portfolio, with fewer equities and more bonds, as they approach and enter retirement. A typical assumption is 3-5% during retirement compared to 5-8% before; the calculator defaults to 4% and 6% respectively.

A large nominal balance can run out early when the inflation-adjusted spending target grows faster than the pot's investment return. For example, if inflation is 2.5% and the retirement return is 4%, the real growth on the pot is only about 1.5% per year while withdrawals grow at 2.5%, and that gap compounds over time. The chart shows both the nominal balance and the inflation-adjusted balance so you can see the divergence between account value and purchasing power.

All contribution frequencies are converted to a monthly equivalent so they can be compared and combined. A weekly contribution of $100 equals $100 × 52 ÷ 12 ≈ $433 per month; an annual contribution of $6,000 equals exactly $500 per month. Each month of the saving phase, the calculator first applies monthly growth to the existing balance and then adds that monthly equivalent, so growth is only earned on money that was invested for the full month. This is the more conservative assumption: adding contributions before growth would overstate returns. All contributions stop when the retirement age is reached.

The summary shows the highest monthly spending, in today's money, that your pot can fund until the plan age, and the same amount in nominal terms at the start of retirement. The calculator finds it with a binary search: it raises or lowers the spending target and repeats the full projection until the money lasts exactly to the plan age. With the default inputs, starting at 35 with $50,000, adding $500 a month, a 6% return before and 4% during retirement, 2.5% inflation, retiring at 67 and planning to 95, the maximum is about $1,452 a month in today's money, or about $3,200 a month in nominal terms when you retire. The default $2,500 target is higher, which is why the pot runs out at about age 81.9. Both figures are shown because the nominal amount is what you would actually withdraw in the first month of retirement, while the amount in today's money tells you what lifestyle it buys.

When the pot runs out before the plan age, the calculator estimates the extra monthly contribution needed from today until retirement to make the money last. It searches for this amount by adding it to the saving phase and repeating the full projection until the plan survives to the chosen age. The figure is sensitive to your assumptions: lower expected returns, higher inflation or a longer retirement all increase the extra monthly contribution needed.

Yes. Use the extra options to add custom lines and mark each one as either income received during retirement or savings added before retirement. A state pension entered as retirement income reduces the amount the pot must pay each month, which lowers the required balance at retirement. A workplace match entered as a pre-retirement contribution is treated as additional savings alongside your regular monthly contribution, and the calculator does not estimate country-specific benefit formulas, tax rules or account limits. For example, entering $1,500 a month of Social Security as retirement income from age 67 reduces the monthly amount the pot itself must cover from $2,500 to $1,000, which can turn a shortfall into a surplus without changing any other input. You can add up to 8 extra lines, so a workplace pension, rental income and a state benefit can each be entered separately with their own frequency and start type.

Yes. Set the retirement age to your intended early retirement age and enter your spending target in today's money. Retiring at 55 instead of 67 leaves 12 fewer saving years and 12 more spending years, which significantly increases the required balance at retirement. The calculator estimates the extra monthly saving needed if the projected pot falls short of supporting the full spending period to your chosen plan age. For example, starting from the same $50,000 and $500 a month, retiring at 55 instead of 67 cuts the saving phase from 32 years to 20 years while stretching the spending phase to 40 years if you still plan to age 95. That combination usually increases the required extra monthly contribution shown in the summary, since the pot has less time to grow and more years of withdrawals to cover, so comparing a few retirement ages side by side is a useful check before committing to one.

With this calculator's retirement assumptions, a 4% return on the money that stays invested and 2.5% inflation, $1,000,000 at age 67 pays $4,000 a month in today's money until about age 91.8, and $5,000 a month until about age 86.2. The most it can pay and still last to 95 is about $3,625 a month, rising each year with inflation. Half the pot, $500,000, gives exactly half the amounts over the same ages: $2,000 a month lasts to about 91.8 and the maximum to 95 is about $1,812 a month. The 4% rule's $40,000 in the first year from $1,000,000, about $3,333 a month, lasts beyond 95 in this model, with about $120,716 left in today's money, because it starts below the $3,625 maximum. To test your own figures, set the current age and the retirement age to the same value, enter your pot as current retirement savings and set the recurring contribution to 0.

The 4% rule comes from the Trinity Study, which tested historical 30-year U.S. market periods and found that withdrawing 4% of a portfolio in the first year of retirement, then raising that amount with inflation, rarely ran out of money. This calculator does not apply a fixed withdrawal rate: it withdraws your monthly spending target and simulates the pot month by month until your plan age. In the default example, $2,500 a month is $30,000 a year in today's money, against a projected balance of about $400,610 in today's money, an initial withdrawal rate of about 7.5%, which is why the money runs out at about age 81.9. The 4% rule would call for $750,000, or 25 times $30,000, while this calculator needs about $689,722 in today's money, because it assumes a steady 4% return during retirement with no bad early years and spends the pot to zero by age 95. Lowering the target to about $1,335 a month brings the withdrawal rate back to 4%.

No. This is an educational planning model that estimates outcomes based on the assumptions you enter. It does not account for your full financial picture, local tax rules, pension rights, healthcare costs, sequence-of-returns risk or individual fee structures. Always consult a qualified financial or pension adviser before making retirement decisions.