What could a £300,000 pension pot grow to — compare the assumptions.
Project a £300,000 pension pot forward with illustrative UK assumptions for growth, contributions, and fees over 10-20 years.
A £300,000 pot at an illustrative 4% withdrawal produces £12,000 a year before tax. Adding a full State Pension gives £24,548 gross, or about £22,152 after illustrative 2026/27 England, Wales and Northern Ireland income tax. The 2026 one-person spending benchmarks outside London are £13,900 minimum, £32,700 moderate and £45,400 comfortable. Rent and mortgage payments are extra. This assumes fully taxable withdrawals and no other income; Scottish tax differs. A 4% withdrawal is not guaranteed sustainable income. Fees, investment returns, retirement length and tax-free cash choices affect the outcome.
Understanding the projection
How does this pension compound-interest calculator work?
For illustration, a starting pot of £300,000, £200 paid into the pension at each month-end, 5% assumed annual growth and a 0.75% annual fee produces about £1,216,361 after 30 years. The model divides growth less fees by 12 and compounds monthly. This is a constant-rate scenario in future pounds, not guaranteed interest or a forecast.
What growth rate should I use?
There is no single reliable rate for every pension. Returns depend on investments, charges and market conditions. Compare several assumptions, including low or negative growth. The default is an illustration, not an FCA-approved forecast or a statement about the suitability of an investment.
How is inflation shown?
The headline, chart and milestones show future pounds. The separate purchasing-power figure divides the final pot by (1 + the annual inflation assumption) raised to the number of years. It shows an equivalent in today's money, before withdrawal tax. Contributions stay fixed in cash terms.
Should contributions include employer payments and tax relief?
Enter the total monthly amount credited to the pension, including employer contributions and any relief credited to it. The calculator adds no extra tax relief and does not check contribution allowances. The starting pot plus payments is different from your personal out-of-pocket cost.
What does the fee comparison show?
It compares two otherwise identical scenarios with and without the selected fee. The difference includes charges and foregone growth. Actual charging structures can differ, and a lower modelled fee is not a recommendation to change pension or investment.
For a broader view of retirement income, see MoneyHelper’s pension calculator.