Retirement Calculator

Retirement is unusual among financial goals because it does not have a fixed end date. A house deposit or a car purchase needs a known sum by a known day; retirement needs an income that keeps arriving for an unknown number of years after the paychecks stop — which could be twenty years or forty, depending on how long you live. That uncertainty is what makes retirement planning harder than simply projecting a savings goal: the pot has to be large enough not just to reach retirement, but to outlast it.

The working assumption behind most retirement planning is income replacement — building enough investment income, pension income and other sources to replace a comfortable share of your working income once the salary disappears, rather than replacing it entirely, since some costs (commuting, saving itself, in some places even certain taxes) tend to fall once you stop working.

Very few people fund retirement from a single source. A realistic plan usually draws on several of the following at once.

When an employer offers to add money on top of what you contribute, that match is effectively an immediate, guaranteed return before the market has done anything at all — no investment carries a comparable guarantee. It usually comes with two limits worth checking against your plan documents: a rate (how much they add per unit you contribute) and a cap (the share of salary above which they stop matching), and contributing below the cap leaves part of that arrangement unclaimed.

One caveat worth knowing before treating a match as already yours: some plans vest employer contributions gradually, meaning you only keep them in full after a set number of years of service. Leaving early can mean forfeiting unvested employer money even though it already appears in your account balance.

Two figures do most of the work in answering this. The first is a target income-replacement ratio — the share of pre-retirement income the plan aims to provide. The second is a sustainable withdrawal rate: the percentage of the final balance that can be drawn each year without a high risk of running out. A widely cited starting point for the second comes from studies of historical market data, though it assumes a particular investment mix and market history and is treated as a rough guide rather than a guarantee by most planners.

The order returns arrive in also matters more than their average. A downturn in the first few years of retirement does far more damage than the same downturn a decade in, because withdrawals are being taken from an already-shrunken balance with less time to recover — a risk retirement planning tends to call sequence-of-returns risk.

A few habits account for most of the difference between retirement plans that stay on schedule and ones that fall short.

For much of the twentieth century, many workers in stable, long-tenure jobs retired into a defined-benefit pension: an employer-guaranteed income for life, calculated from salary and years of service, with the investment risk sitting on the employer’s balance sheet. Over recent decades that model has substantially given way to defined-contribution plans, where the employer’s obligation ends once the contribution is made and the investment risk, and the responsibility for making the money last, sits with the individual instead.

That shift is the reason calculators like this one exist at all — a defined-benefit pension needed no projection, because the payout was promised regardless of markets. A defined-contribution balance needs exactly the kind of forward modelling this calculator provides, because nobody else is guaranteeing the outcome.