Retirement Calculator

The question this calculator actually answers

"How much will I have at retirement?" is a less useful question than "how much will my spending power be, given my plan and a realistic range of outcomes?" The figure this tool produces is the central estimate under the assumptions you enter. The shape of the answer — how much it shifts when you

The four inputs that do 80% of the work

The result here depends almost entirely on four things: current age, target retirement age, contribution rate, and return assumption. Everything else — starting pot size, withdrawal rate, inflation — affects the answer at the margins. If you only adjust one variable for a quick sensitivity check, adjust the return assumption. The difference between a 5% and 7% real return over 30 years doubles or halves the ending pot in ways that dwarf other variables.

What "enough" actually means

The most common retirement-planning heuristic is the 25x rule: you need 25 times your annual expenses invested at retirement to sustain 30+ years of withdrawals at a 4% rate. Spend 30,000 a year in retirement? You need 750,000. Spend 50,000? You need 1.25m. The 4% figure comes from the Trinity Study (1998), which tested historical data and found a 4% inflation-adjusted withdrawal succeeded in 95%+ of 30-year retirement windows. It's a rule of thumb, not a guarantee — but it's the most-cited benchmark and a useful starting reference.

Why the 4% rule has aged

The Trinity Study used 1926–1995 data. Three things have changed since: life expectancy is longer (a 65-year-old today has a meaningful chance of a 35-year retirement, stressing the plan beyond 30 years), bond yields have been lower than historical averages, and equity valuations at the start of some retirement windows have been higher. Some researchers now suggest 3.0–3.3% as a more conservative starting withdrawal rate. Morningstar's 2023 analysis suggested 3.8%. The 4% number is still a reasonable central estimate, but treating it as a ceiling rather than a guide is increasingly wise.

Sequence of returns: the hidden risk

The most dangerous thing in retirement isn't market returns — it's when those returns happen. Two retirees with identical 30-year average returns can end with wildly different outcomes depending on whether the losses came early or late. A 30% market drop in year three of retirement, before the pot has had time to grow, is far more damaging than the same drop in year 25. This is called sequence-of-returns risk, and it's the single biggest reason why conservative withdrawal rates in early retirement matter more than average returns across the whole period.

UK pension situation specifically

For residents, the state pension provides a floor — currently around 11,500 annually for full payroll tax contributions. That's not a retirement — it's a top-up. Occupational or personal pensions fill the gap, with tax relief on contributions making pensions the most tax-efficient long-term savings vehicle available. Workplace pensions with employer match are an additional employer-funded contribution; skipping the match is mathematically close to refusing part of your salary. The calculator here doesn't distinguish between pension types, but the tax-relief boost on contributions typically adds 20–40% to the effective contribution rate depending on your income band.

Longevity: plan for a longer retirement than your parents had

A 65-year-old man today has a 50% chance of living to 86, a 25% chance of living to 91, and roughly a 5% chance of reaching 100. Women's numbers are several years higher. Planning a pot to last to 85 has a meaningful probability of running out; planning to 95 is closer to responsible. The calculator lets you set retirement age — set a realistic end-of-plan age too and see how the required pot changes.

The three levers when the projected pot is too small

If the tool says you're short, you have three ways to close the gap, in order of financial powerwork longer (the biggest lever — each extra year is one more year of contributions, one less year of withdrawals, and later state pension access), contribute more (less powerful than working longer but more certain than return assumptions), and increase return assumptions (the least reliable — you can't choose to earn higher returns, only expose yourself to more volatility). Most financial advisers push the first two hard before discussing the third.

What the projection can't tell you

The calculator produces a deterministic path — one return, one contribution rate, one retirement age. Real retirements involve variable returns, changing contributions, health events, inheritances, moving in with family, and partial work in later years. Most retirement plans survive contact with reality only if they're revisited annually. The point of running this calculator isn't to be right in 30 years — it's to be less wrong about the plan you're putting in place this year.