Retirement Savings Calculator
The two variables that matter most are how early you start and whether you are claiming the full employer match. Investment returns come third.
Take the employer match first
Look at the last row of the results. The gap between the full projection and the one excluding employer contributions is usually enormous — frequently a third or more of the final pot.
An employer match is an immediate, guaranteed return on the money you contribute. A pound-for-pound match is a 100 % return before any investment growth. No fund, no strategy and no asset class offers anything comparable, and it is available to most employed people simply by increasing a contribution percentage on a form.
Not claiming the full match is the single most expensive common mistake in personal finance. If you do one thing after reading this page, check what your employer will match and whether you are contributing enough to receive all of it.
Why starting early beats contributing more
Compare two savers, both contributing £200 a month at 5 % growth:
| Starts at 25 | Starts at 40 | |
|---|---|---|
| Years contributing | 42 | 27 |
| Total contributed | £100,800 | £64,800 |
| Pot at 67 | ~£345,000 | ~£163,000 |
| Growth as a share of the pot | 71 % | 60 % |
The later starter contributes 64 % as much and ends with 47 % of the pot. To catch up, they would need to contribute roughly £420 a month rather than £200.
This is why the standard advice to increase your contribution whenever you get a pay rise works so well: it raises the amount without reducing your current spending, and it does so early.
Turning a pot into an income
The 4 % figure in the results comes from research on sustainable withdrawal rates — the proportion of a portfolio that could historically be withdrawn annually, adjusted for inflation, without running out over a 30-year retirement.
Important caveats. The original research was based on US market history and a specific asset allocation, and later work has suggested 3–3.5 % may be more prudent for longer retirements or lower expected returns. It also assumes a spending pattern that does not vary, which real retirements do not follow. And in many countries a state pension covers part of the requirement, reducing what the pot must provide.
Treat it as a way of turning a pot into a rough income, and a way of turning a target income into a rough pot — not as a withdrawal plan.
What this projection cannot know
- Returns are not smooth. This model applies a constant growth rate. Real markets do not, and the order in which good and bad years arrive matters a great deal near retirement.
- Fees compound too. Enter a growth rate net of charges. A 1 % annual fee on a 6 % gross return removes roughly a quarter of the final pot over 30 years.
- Salary changes. Contributions as a percentage of salary rise with pay, which this does not model.
- Tax relief and limits vary by country and materially affect the real cost of contributing.
- State pension is not included.
Use it to compare scenarios — what does contributing two percent more do? what does retiring three years later do? — rather than as a forecast of a specific number.
Frequently asked questions
How much should I be contributing?
A frequently cited rule of thumb is to halve your age when you start and contribute that percentage of salary, including the employer's share — so 15 % if you start at 30. What matters more is claiming the full employer match and increasing the rate with each pay rise.
Is it too late if I am starting at 50?
No, though the arithmetic is harder. You have fewer years of compounding, so contributions do more of the work. Many countries also allow higher contributions later in life, and working a few years longer has a disproportionate effect — it adds contributions and removes years of withdrawals simultaneously.
What growth rate should I assume?
Something conservative. Many planners use 4–5 % net of fees for a diversified portfolio. Test the projection at 3 % as well — if the plan only works at 8 %, it is not a plan.
Should I include the state pension?
Not in this calculation, which models your own pot. Do include it when working out the income you need the pot to provide — in many countries it covers a meaningful share of basic expenses.