Retirement Calculator UK
Estimate your FIRE number, when your investments could reach it, and the monthly saving needed for a target age.
At your target age
Reaching the target by your chosen age needs £605.21 a month more than you put away today.
The same spending at other withdrawal rates
Figures are estimates in today’s money after the inflation and fee assumptions.
Pension access ages and tax on withdrawals are not modelled; check the rules for each account.
The 4% rule is a planning guideline, not a guarantee. Returns and sustainable withdrawals can vary.
How the pot could grow
The balance in today’s money at the end of each year, against the FIRE target it has to clear.
Year-by-year projection
What each year opens with, the contributions you add and the real growth on top, through to age 100.
| Year | Age | Opening balance | Contributions | Real growth | Closing balance |
|---|---|---|---|---|---|
| 1 | 31 | £50,000.00 | £12,000.00 | £1,346.12 | £63,346.12 |
| 2 | 32 | £63,346.12 | £12,000.00 | £1,669.95 | £77,016.07 |
| 3 | 33 | £77,016.07 | £12,000.00 | £2,001.65 | £91,017.72 |
| 4 | 34 | £91,017.72 | £12,000.00 | £2,341.37 | £105,359.09 |
| 5 | 35 | £105,359.09 | £12,000.00 | £2,689.39 | £120,048.48 |
| 6 | 36 | £120,048.48 | £12,000.00 | £3,045.83 | £135,094.31 |
| 7 | 37 | £135,094.31 | £12,000.00 | £3,410.90 | £150,505.21 |
| 8 | 38 | £150,505.21 | £12,000.00 | £3,784.86 | £166,290.07 |
| 9 | 39 | £166,290.07 | £12,000.00 | £4,167.87 | £182,457.94 |
| 10 | 40 | £182,457.94 | £12,000.00 | £4,560.15 | £199,018.09 |
JavaScript is required to edit this calculation. The page contains an illustrative example before it loads.
Shareable links contain the figures you enter. They can appear in browser history or be disclosed when shared.
How the retirement estimate works
The FIRE target
Your FIRE target is annual spending divided by the withdrawal rate. For example, £30,000 divided by 4% gives £750,000. A lower withdrawal rate produces a larger target. This is a planning shortcut rather than a promise that a portfolio will last.
The month-by-month projection
The projection converts your annual assumptions to one real monthly growth rate: ((1 + return) × (1 − fees) ÷ (1 + inflation))^(1/12) − 1. Growth is applied first and your contribution is added at month end. Contributions are treated as today’s-money amounts, so the nominal payment would need to rise with inflation to keep that purchasing power.
The same month-by-month schedule supplies every headline, chart point, table row and target-age saving result. Values are stored in whole pence; monthly growth rounds half away from zero and the FIRE target rounds upward.
What the estimate leaves out
It assumes a constant return, inflation and fee rate. Real markets vary and investments can lose money. The estimate does not model market sequence, income changes, one-off spending, tax, State Pension, defined-benefit income or the rules of a particular account.
Pension money may not be accessible at your chosen FIRE age and withdrawals can be taxable. Check each account’s access rules and consider regulated financial advice for decisions based on your circumstances.
Sources and further guidance
Sold shares, funds or crypto this year?
HMRC-ready Capital Gains Tax report from your broker statement — free to start.
Frequently asked questions
What is a FIRE number?
+
It is the invested capital implied by your annual spending and chosen withdrawal rate. At £30,000 spending and 4%, the estimate is £750,000.
Does the 4% rule guarantee my money will last?
+
No. It is a planning guideline, not a guarantee. Actual returns, inflation, fees, tax, spending changes and the order of market gains and losses can materially change the outcome.
Why are the results shown in today’s money?
+
Removing assumed inflation makes projected balances comparable with what your spending buys today. The calculator treats monthly contributions the same way, so their nominal amount would need to rise with inflation.
Can I retire before I can access a pension?
+
Only if accessible savings and other income can cover the gap. This calculator combines capital into one projection and does not enforce pension access ages, which vary by account and rules.
Does this calculator include tax or the State Pension?
+
No. It does not model tax on withdrawals, State Pension, defined-benefit pensions or account-specific reliefs. Treat the result as an illustrative investment target.