Retirement Calculator: Project Your Pension Pot

Use the retirement calculator above

Enter your current age, target retirement age, what you already have saved, your monthly contribution and an expected yearly growth rate. The tool projects your pot at retirement and shows how much of the final figure comes from your own money versus investment growth. Adjust the inputs to see how a small change today compounds over decades.

How the retirement calculator works

The maths behind it is compound growth applied to two things: any lump sum you already hold, and the stream of regular contributions you keep adding. In plain terms:

Final pot = (starting pot grown for the full term) + (each contribution grown for the time it stays invested).

For the lump sum, the formula is the standard compound one: Future value = present amount × (1 + r)ⁿ, where r is the yearly growth rate as a decimal and n is the number of years. For your regular payments, the calculator uses the future value of a series of contributions: FV = annual contribution × [((1 + r)ⁿ − 1) / r]. Money you pay in early has more years to grow, so it does the heavy lifting.

Two things matter more than people expect. First, the growth rate: returns are never guaranteed, so the figure you type is an assumption, not a promise. A diversified fund might be modelled at 4–6% a year before charges and inflation, but markets fall as well as rise. Second, time. Thirty years of compounding turns a modest monthly habit into a six-figure pot, which is why starting in your twenties beats starting in your forties even if the older saver pays in more each month. The calculator shows results in today's loose terms; remember that inflation erodes what a pound buys, so a pot of £300,000 in 30 years will not stretch as far as £300,000 today.

One UK-specific boost the projection can capture is pension tax relief. Pay into a pension and the government tops up your contribution: a basic-rate taxpayer's £80 becomes £100 in the pension, because the 20% that would have gone in income tax is added back. Higher and additional-rate taxpayers can claim more through Self Assessment. That relief is effectively free growth before any investment return, which is why a pension often beats an ISA for long-term retirement saving even though both are tax-efficient.

Worked example: a 35-year-old saving for 30 years

Say you are 35, want to retire at 65, and pay £200 a month (£2,400 a year) into a pension assuming 5% annual growth. Using the series formula with r = 0.05 and n = 30, the growth factor is ((1.05³⁰ − 1) / 0.05) = 66.439.

• Your own contributions over 30 years: 30 × £2,400 = £72,000.
• Projected pot from net £2,400/year: £2,400 × 66.439 = £159,453.
• So roughly £87,000 of that pot is investment growth you never paid in.

Now add pension tax relief. As a basic-rate taxpayer, your £2,400 net becomes £3,000 gross in the pension (£2,400 ÷ 0.8). Same 5% growth, same 30 years: £3,000 × 66.439 = £199,317. The relief alone has added almost £40,000 to the final pot at no extra cost to you.

Worked example: a lump sum left to grow

Compounding rewards money you can leave untouched. Put £20,000 into a fund returning 6% a year and leave it for 20 years: £20,000 × 1.06²⁰ = £20,000 × 3.2071 = £64,143. You more than tripled it without adding a penny, purely through time and reinvested growth.

Combine both habits and the numbers get serious. A £25,000 starting pot plus £250 a month (£3,000 a year), both growing at 6% for 25 years, projects to about £271,890 — roughly £107,300 from the lump sum and £164,600 from the regular payments. Use our compound interest calculator to stress-test these growth assumptions, and the pension pot calculator to model contribution changes.

When can I afford to retire?

A common rule of thumb is to aim for a pot that can replace a meaningful share of your working income each year once the State Pension is added on top. Two levers decide your retirement date: the pot you build and how much you draw from it each year. Drawing too hard early on risks running out; drawing cautiously means working longer. The honest answer to "when can I afford to retire" comes from running your projected pot through a sustainable withdrawal plan, then checking the gap against your expected spending.

Do not forget the State Pension. It usually forms the floor of UK retirement income, but it starts at State Pension age, not when you choose to stop. Check your forecast and qualifying years on your State Pension forecast and confirm when payments begin with the State Pension age calculator, because any years before that age must be funded entirely from your own savings.

Tax rules worth planning around

You can pay a lot into a pension, but tax relief is capped. The pension Annual Allowance for 2026/27 is £60,000 (or 100% of your earnings if lower), and it tapers for very high earners. An ISA gives you a separate £20,000 tax-free allowance each year, useful for money you might want before pension access age. When you eventually retire, you can normally take part of a defined contribution pension as a tax-free lump sum (commonly up to a quarter of the pot), with the rest taxed as income when withdrawn — so how you draw matters as much as how you save.

Income tax in retirement follows the same bands as working life, and those bands differ in Scotland, where the Scottish Parliament sets its own rates and thresholds on non-savings income. A Scottish taxpayer drawing a large pension income could face different marginal rates than someone in England, Wales or Northern Ireland, so factor your nation into any drawdown plan. For the official rules on relief and allowances, see gov.uk: tax on your private pension, and for impartial guidance read MoneyHelper's pensions hub.

Common mistakes to avoid

• Assuming an unrealistic growth rate. Typing 10% makes the pot look huge but sets you up to fall short. Model a cautious return and treat anything above it as a bonus.
• Ignoring charges and inflation. A 1% annual fund charge quietly shaves tens of thousands off a long projection, and inflation reduces what your pot buys.
• Leaving tax relief and employer matching on the table. If your employer matches contributions, not paying in enough to get the full match is turning down free money.
• Stopping when you change jobs. Dormant pots and paused contributions break the compounding chain. Keep paying in and consider consolidating old pots.
• Forgetting access age. You cannot usually touch a private pension until the normal minimum pension age, so plan separate savings for an earlier finish.

Related calculators

To go deeper, model regular contributions with the pension calculator, test an early-retirement target with the FIRE calculator, or see what your savings could pay out using the pension drawdown calculator.

These figures are estimates for guidance only and are not personal tax or financial advice. Investment returns are not guaranteed and the value of investments can fall as well as rise.

The numbers: pension limits and what relief is worth

Official guidance: GOV.UK pension tax and free advice from MoneyHelper.