About this tool

How to use the retirement savings calculator

Working through the inputs in order produces the most useful result. The steps below explain what each input does and how the tool’s panels build on each other.

How compound growth works in a pension projection

The core principle behind a retirement projection is that returns earned in one period are reinvested and themselves earn returns in subsequent periods. This compounding effect is modest in the early years of saving and becomes increasingly significant as the pot grows larger and the time horizon extends. A pot of £50,000 earning 5% per year generates £2,500 in returns in year one. A pot of £200,000 at the same rate generates £10,000. The contributions remain constant in the simplified model, but the returns component keeps growing in absolute terms as the pot compounds.

This dynamic explains why starting earlier has a disproportionately large effect on the final pot size compared with simply saving more money over a shorter period. A 30-year-old saving £300 per month at 5% per year for 35 years reaches a larger pot than a 40-year-old saving £600 per month at the same rate for 25 years, even though the second person is contributing more each month. The additional decade of compounding in the first scenario outweighs the higher monthly saving in the second. The tool’s start-later panel illustrates this relationship directly for your specific inputs: the monthly saving gap shown is not linear because the missing years are the ones where compounding would have had the longest to run.

The State Pension and your personal retirement target

The new full State Pension for 2025/26 is £11,502 per year for those with the qualifying National Insurance record. The tool uses this figure to calculate an illustrative equivalent pot: at a 4% drawdown rate, £11,502 per year corresponds to a pot of approximately £287,550. The State Pension toggle shows this calculation and subtracts it from your personal target to give an adjusted gap that your own saving needs to fill. This is a simplification rather than a precise calculation, because the State Pension is paid as a guaranteed income rather than drawn from a personal pot, and it is subject to changes in government policy.

Your actual State Pension entitlement depends on your National Insurance record, including years of contributions, credits received for periods of caring or unemployment, and whether any years are missing. The government’s Check Your State Pension forecast service on GOV.UK provides a personalised projection based on your National Insurance record and is the most accurate source for planning purposes. The toggle in this tool is designed to give a rough sense of how the State Pension adjusts the monthly saving needed, not to substitute for checking your actual entitlement. If you have gaps in your National Insurance record, it may be possible to fill some of them voluntarily, which is worth exploring before assuming a full entitlement.

Making your contributions work harder over time

The contribution increase slider models an escalating saving strategy where monthly contributions grow by a fixed percentage each year. The underlying logic is that salary growth, if it occurs, creates the capacity to increase saving without proportionally reducing take-home pay. A saver who increases contributions by 3% each year in line with salary growth commits to a starting figure that is lower than a flat-contribution plan, but matches or exceeds it later in the projection when the compounding on those additional contributions still has several years to run.

In practice, pension contributions through an employer scheme often have a minimum that rises automatically, and many schemes allow voluntary additional contributions that can be increased incrementally. The tool does not model the tax relief element of pension contributions, which for a basic rate taxpayer effectively means that £80 contributed produces £100 in the pension wrapper, or for a higher rate taxpayer that £60 produces £100. This tax efficiency means that the gross monthly saving required is lower than the net cash cost for most pension savers, and the actual cash commitment from salary is smaller than the headline figure the tool calculates. Taking this into account when assessing affordability is particularly important for higher earners where the relief is more substantial.

The real cost of delaying your contributions

The start-later panel quantifies what is lost by beginning contributions five years after the current date. The shortfall it shows is typically larger than most people expect, for two reasons. First, the five missing years would have contained contributions that compound for the longest remaining period of the projection. Second, the existing savings balance, if there is one, would also have had five additional years to compound. The combination of both effects means the shortfall in the final pot grows faster than five years’ worth of contributions would suggest.

The panel also shows the additional monthly saving required to reach the same target if starting five years later. This extra amount is typically considerably higher than the original monthly saving, because the shorter remaining term means each additional pound of saving has less time to compound. The implication is that waiting and then saving more rarely produces an equivalent outcome to saving less and starting sooner. This is the mathematical case for beginning pension contributions at the earliest practical opportunity, regardless of the amount. A small regular contribution started early is not equivalent to a larger contribution started later; it is structurally more efficient because the compounding advantage cannot be replicated by increasing the saving rate after the delay has already occurred.

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Frequently asked questions

How accurate are the projections this calculator produces?

The projections are illustrative only. They apply a fixed annual return rate to a growing pot across the full term, which means they do not reflect the year-to-year variation in real investment returns, the effect of charges, the impact of inflation on the real value of the final pot, or any gaps in contributions. A projection at 5% per year does not mean your pot will grow at exactly 5% annually; it means the tool applies 5% as a constant assumption to show the mathematical effect of compounding at that rate.

In practice, a diversified investment portfolio will produce returns that vary significantly from year to year. Some years will outperform the assumed rate; others will underperform or produce negative returns. Over long periods, average returns tend to smooth out, but the sequence of those returns matters: poor returns in the early accumulation phase have a different impact than the same average return achieved in a different sequence. The projections here are useful for understanding the order of magnitude of saving required and the relative impact of different variables. For precise retirement planning, a regulated financial adviser can model more detailed scenarios using actuarial assumptions and your specific pension arrangements.

What return rate should I use in the calculator?

There is no universally correct answer, because the appropriate assumed return depends on how the pot is invested, the time horizon, and the level of risk taken. As a general reference, the Financial Conduct Authority uses standardised projection rates of 2%, 5%, and 8% per year for pension illustration purposes, where the middle rate (5%) is typically used as a central estimate for a mixed asset portfolio. A more conservative saver who holds a higher proportion of bonds or cash-like assets might use a lower rate; a saver with a long time horizon invested primarily in equities might use a higher one.

For comparison purposes, looking at more than one return rate is more informative than fixing on a single figure. Setting the tool to 3%, 5%, and 7% and noting the monthly saving required under each scenario gives a range rather than a single projected figure, which is more honest about the uncertainty in long-run investment returns. The tool does not charge the returns figure for fund management costs, platform fees, or adviser charges, all of which reduce the net return. Subtracting estimated annual charges from the gross return when setting the slider produces a more conservative and more realistic projection.

Does the calculator take tax relief on pension contributions into account?

The tool does not model pension tax relief, so the monthly saving figure it calculates represents the gross contribution that needs to reach the pension wrapper rather than the net cash cost from your salary. For a basic rate taxpayer, pension tax relief means that a £100 contribution to the pension costs £80 from take-home pay, because the government adds £20 in basic rate relief. For a higher rate taxpayer, the same £100 contribution can cost as little as £60 after claiming higher rate relief through self-assessment. The actual cash commitment is therefore lower than the headline figure for most pension savers.

To estimate the real cash cost of the monthly saving figure the tool calculates, divide by 0.80 for the basic rate tax position (£125 gross contribution costs £100 net) or by 0.60 for the higher rate position (£125 gross costs £75 net). Employer contributions, where applicable, add a further layer: if your employer contributes a percentage of salary to your pension, that amount reduces the gap your own contributions need to fill. The tool’s “current savings” input can be used to model existing pension balances, but employer contributions going forward are not explicitly modelled as a separate input.

Should I save into a pension or an ISA for retirement?

Both pensions and Stocks and Shares ISAs can be used to accumulate a retirement pot. Pensions benefit from upfront tax relief on contributions, and employers are required to contribute under auto-enrolment if you are eligible, which makes them highly efficient for most employed savers. The trade-off is that pension funds are generally inaccessible until age 57 (rising to 58 in 2028 under current legislation), and withdrawals above the 25% tax-free lump sum are taxable as income. A Stocks and Shares ISA offers no upfront tax relief, but withdrawals are entirely tax-free and the funds are accessible at any time.

The most appropriate structure depends on your tax position, accessibility needs, employer contribution arrangements, and the amount you are saving relative to the annual pension and ISA allowances. Many people use a combination of both, prioritising pension contributions up to the employer match level (to capture the matched employer contribution) and then using an ISA for additional saving that benefits from flexible access. This tool calculates a pot target and monthly saving requirement without specifying the wrapper: you can use the figures as inputs to your broader planning regardless of whether the saving goes into a pension, an ISA, or a combination of the two. The ISA vs loan cost comparison tool explores some of the dynamics around ISA savings and opportunity cost in more detail.

What if the monthly saving the calculator suggests is more than I can afford right now?

The tool calculates what is mathematically required to reach a chosen target by a chosen date, not what is affordable for any individual. If the figure is higher than your current budget allows, there are several ways to use the tool to explore alternatives. Adjusting the target pot downward, extending the retirement age, or increasing the assumed return rate each reduce the required monthly saving, at the cost of either a smaller pot, a later retirement date, or a higher assumed risk. The start-later panel shows how much more expensive delay is, which is relevant if you are considering whether to begin at a lower amount now or wait until circumstances improve.

In practice, starting with a smaller contribution and increasing it over time as income grows is a widely used approach. The contribution increase slider in the tool models this: setting a growth rate of 2 or 3% per year shows a lower initial monthly saving requirement at the cost of higher contributions later. Even a small initial contribution is more useful than no contribution, both for the compounding effect on the amount saved and for establishing the habit and the auto-enrolment or direct debit mechanism that can be increased later. If outstanding debt is competing with your ability to save, the pay down debt vs save comparator helps model how different allocations between debt repayment and saving affect net worth over time.

This tool is for illustrative purposes only and does not constitute financial advice. Pension and retirement projections depend entirely on the inputs provided and apply simplified assumptions that will not reflect real-world investment conditions, charges, tax treatment, or inflation. Past investment performance is not a guide to future returns. The State Pension figures used are based on the 2025/26 illustrative rate and are subject to change. Actual outcomes will depend on your individual circumstances, and you should consider seeking regulated financial advice before making decisions about retirement saving or pension arrangements.