One question, answered with arithmetic: how many years of spending does a pension pot actually buy? Three pot sizes, three spending levels, every assumption on the table. Nothing promised, nothing sold.
Every pot-longevity number depends entirely on the assumptions behind it. Change the growth rate by two points and the answer moves by a decade. So the assumptions come first, not in a footnote.
Information and guidance only. Not personal advice. These are illustrative calculations for fictional pot sizes, not recommendations. Investment values can fall as well as rise and you may get back less than you put in. Verify decisions with a qualified FCA-authorised adviser before acting.
Read it as: with the assumptions above, a £500,000 pot supporting £30,000 a year of spending in today's money runs out during year 22. "Doesn't run out" means the real growth on the pot covers the withdrawal indefinitely under these assumptions.
| Pot at retirement | £20,000 / yr | £30,000 / yr | £40,000 / yr |
|---|---|---|---|
| £250,000 | 15 years | 10 years | 7 years |
| £500,000 | 39 years | 22 years | 15 years |
| £1,000,000 | Doesn't run out | 68 years | 39 years |
A common reference point: a 4% first-year withdrawal (the classic rule-of-thumb starting rate, used as the Sonuswealth engine default) means £10,000 a year from £250,000, £20,000 from £500,000, and £40,000 from £1,000,000. Whether 4% is sustainable for a given household depends on age, other income, and how flexible spending can be. It is a starting point for a conversation, not a law.
The engine draws an uncertainty band of two percentage points either side of the growth assumption. Here is what that band does to the middle case, plus the effect of retiring two years earlier or later.
| Scenario (£500,000 pot, £30,000 / yr) | Pot lasts |
|---|---|
| Base case: 2.5% real growth | 22 years |
| Weak returns: 0.5% real growth | 18 years (4 years fewer) |
| Strong returns: 4.5% real growth | 29 years (7 years more) |
| Retire 2 years later: pot grows untouched to roughly £525,000 first | 23 years from the later start |
| Retire 2 years earlier | Same 22 years of cover, but they start 2 years sooner, so the money-runs-out age drops by 2 years |
The honest reading: the growth assumption you cannot control moves the answer by more than a decade across the band. The retirement date you partly can control moves it by roughly the number of years you shift. That asymmetry is why sequence of returns in the first decade matters so much, and why a fixed table like this is a map, not the territory.
The full new state pension in 2026/27 is £12,548 a year (£241.30 a week, with 35 qualifying National Insurance years, from state pension age, currently moving from 66 to 67 by 2028).
Once it starts, a £30,000 spending level needs only £17,452 a year from the pot. That single change roughly doubles how long the middle-case pot lasts. Any realistic retirement plan models the pot and the state pension together, plus any defined benefit pension, which is exactly what a pot-only table cannot show.
In England, local-authority help with care costs is means-tested. With capital above £23,250 a person fully self-funds; between £14,250 and £23,250 a tariff income applies (2026/27 limits).
A pot that "lasts 22 years" can be consumed far faster if residential care is needed, and the means test means savings are largely spent before state support begins. None of the rows above model care costs. It is the single biggest unmodelled risk in most DIY retirement sums, and one reason the answer to "will my money last" is a moving picture rather than one table.
Methodology. Calculations use the Sonuswealth rules bundle UK-2026.1.1 (tax year 2026/27): growth default 5% nominal, inflation 2.5%, sensitivity band ±2 percentage points, state pension £12,548, care means-test limits £23,250 / £14,250. Withdrawals modelled at the start of each year in constant today's-money terms; the pot grows at the real rate on the remainder. All arithmetic machine-checked before publication. Published 7 August 2026 · figures last verified 7 August 2026.
Sonuswealth is pre-launch. The app models this with your actual pot, your state pension record, and your spending, kept current as rules change.