UK Pension Calculator

Most people have a rough idea of how much is in their pension today, but a much fuzzier idea of what that pot might actually be worth by the time they retire, or what income it could realistically provide. This calculator projects your pension pot forward to your chosen retirement age, using your current savings, ongoing contributions and an expected rate of return, then estimates a possible annual income using the well-known 4% drawdown rule.

How to use the pension calculator

Enter your current age, the age you plan to retire, your current pension pot, your own monthly contribution, your employer's monthly contribution, and the annual return you expect your investments to achieve. The calculator then projects your pot at retirement, splits it between what you contributed and what came from investment growth, and estimates a possible annual and monthly income in retirement.

It is worth entering your target annual income too, so the calculator can show whether your current plan is on track or whether there is a gap. Running the numbers a few different ways, with a slightly higher contribution or a later retirement age, often shows how much difference a relatively small change can make over a long time horizon.

How the projection works

Each month, your combined personal and employer contributions are added to your pot, then growth is applied to the new, larger balance, the same compounding principle used by our compound interest calculator. This repeats every month until your chosen retirement age. Once the projected pot is calculated, the 4% rule is applied to estimate a sustainable starting annual income: 4% of your pot in the first year of retirement, with the expectation that this amount would be adjusted for inflation in later years.

The 4% figure comes from historical research into how withdrawal rates have performed against past investment returns and inflation over long retirement periods. It is a helpful planning benchmark rather than a promise, since future returns, inflation and how long your retirement lasts can all differ from the historical periods the rule was built on.

Worked example

Take someone aged 30, planning to retire at 67, a gap of 37 years. They currently have £15,000 in their pension, pay in £300 a month themselves, and their employer adds a further £200 a month, with an assumed 5% average annual return.

Over 37 years, the calculator projects a pension pot of around £737,950. Applying the 4% rule to that pot suggests a starting annual income of roughly £29,518, or about £2,460 a month, before the State Pension is added on top. For someone with a full National Insurance record, the new State Pension currently adds up to a further £12,534.60 a year, taking a combined estimated income to somewhere in the region of £42,000 a year.

Try lowering the assumed return to 3% in the calculator above with the same contributions. The projected pot falls noticeably, which shows how sensitive long-term projections are to the return assumption, and why it is worth being realistic rather than optimistic when choosing a figure to plan around.

Common mistakes to avoid

A frequent mistake is assuming investment returns will be smooth and consistent every year. In reality, pension investments can rise and fall considerably from one year to the next, especially if invested heavily in shares, even though the long-term average may land close to the figure you enter. Treat any projection as a rough guide across decades, not a precise forecast for any single year.

It is also easy to underestimate how much a small increase in contributions matters when there are many years left until retirement. Because of compounding, an extra 1% or 2% of salary paid in during your thirties can end up worth considerably more at retirement than the same percentage increase started in your fifties, simply because it has so much longer to grow.

Finally, do not forget to check your pension charges. Annual management fees, even ones that look small, such as 1% versus 0.5%, compound in the same way your contributions do, and can meaningfully reduce your final pot over several decades. This calculator does not account for charges, so treat its output as a before-fees estimate.

Related calculators

If you would rather save outside a pension wrapper, our ISA calculator shows how a Stocks and Shares or Lifetime ISA could grow tax-free instead. Our compound interest calculator breaks down the same underlying growth maths in more detail, and checking your take-home pay will help you see how much room you realistically have to increase your pension contributions. For more on how pension contributions interact with tax, see our income tax guide, and for the maths behind long-term growth, read our guide to compound interest.