How much to save for retirement: target income, multiplier, path

"How much do I need to retire?" is the question every retirement conversation collapses into, and the honest answer has three parts: a target income, a multiplier that converts it into a pot, and an uncomfortable admission that both rest on assumptions. None of that makes the maths useless — it makes it a planning tool instead of a prophecy, which is exactly how it should be used.

Step one: the income, not the number

Start from what retirement should pay, not what the pot should be. The standard frame separates three layers: the essentials (housing, food, utilities, insurance), the comfortable extras (holidays, eating out, a car that works), and the luxuries. Research bodies in the UK publish annual figures for minimum, moderate and comfortable retirement lifestyles; the US equivalent conversations run on similar tiers. Two adjustments personalise any published figure: your housing position (a paid-off mortgage collapses the essentials tier — the mortgage guide is doing double duty as retirement planning), and your state pension, which covers a slice of the essentials before private money is touched. Target income = the lifestyle tier you want, minus the state floor. The state pensions guide shows how to check that floor precisely.

Step two: the 25× multiplier, and its fine print

The famous shortcut converts annual income into a target pot: the 4% rule — withdraw 4% of the pot in year one, adjust with inflation thereafter, and history (US data, the "Trinity study" lineage) says a 60/40 portfolio survived thirty years in the large majority of scenarios. Invert it and the target pot is 25× your target annual withdrawal: £30,000 a year needs roughly £750,000, minus whatever the state pays. The fine print is where honesty lives: the evidence is historical and US-centric; sequence-of-returns risk (a crash in your first retirement years) is the rule's known weak spot; safe percentages are lower for longer retirements and higher equity exposure; and no rule survives an equity-free pot in an inflationary world. Treat 25× as the middle of a 20–33× planning range, not a law of nature — and the savings goal calculator converts any target into the monthly contribution at a chosen rate, which is the number you can actually act on.

Step three: the contribution path, backwards

The pot target is only useful as a schedule. The compounding arithmetic is unforgiving in one direction and generous in the other: because growth compounds, the same final pot costs dramatically less per month when started at 25 than at 45 — the compound interest guide shows the curves. The practical recipe: take the target, subtract the projected state pension and any existing pots, feed the gap and your age into the calculator, and read off the monthly number at a conservative real return (inflation-adjusted 3–4%, not the bull-market fantasy). Then sequence the money properly: emergency fund and high-interest debt first (the ladder guide), employer match captured, wrappers filled, index funds inside, and the whole thing automated on the DCA discipline.

The final honest note: the number will be wrong. Markets, health, housing and lifespan will all move. What the calculation buys is not certainty but course-correction — a number checked once a year tells you within a few percentage points whether the plan is on track, decades before the runway matters. Retirement is not a cliff you arrive at; it is a glide path you steer, and 25× is the instrument panel, not the destination.

Sources and further reading

Links were reviewed 2026-09-25. Regulatory permissions, firm status and product terms can change; use the current official register before acting.

1. GOV.UK — plan for your retirement
2. MoneyHelper — how much do I need for a comfortable retirement

Keep learning

• How state pensions work: the largest product you never read
• Savings goal calculator
• Compound interest explained: formula, rule of 72, examples