Investment growth
See how a lump sum and regular contributions could grow with compound returns. Good for ISAs, pensions or general investing.
Your plan
Where it comes from
Returns are assumed steady and compounded monthly — real markets rise and fall. Figures are before inflation, fees and tax. Investments can fall as well as rise.
Compound growth, shown rather than described
Start with £5,000, add £300 a month, grow at 6% a year: after 20 years the pot is £155,163. You put in £77,000 of that; growth contributed £78,163. Somewhere around year 19 the market's contribution overtakes yours, and that crossover is the entire argument for starting early and staying in. Stop at 10 years instead and the pot is £58,261, so the second decade added nearly £97,000 against the first decade's £53,000. Same contributions, same rate. Time is doing the heavy lifting.
The two quiet leaks: fees and tax
A 1% annual fee sounds like nothing and behaves like a predator. Run the same 20 years at 5% instead of 6% and the pot lands at £136,873, £18,290 lighter, most of it growth that never got the chance to compound. Platform and fund fees deserve the same scrutiny as returns, because they're the one part of investing you control completely. Tax is the other leak, and it's optional for most people: inside a stocks and shares ISA, up to £20,000 of contributions a year, growth and withdrawals attract no tax at all. Outside one, dividends and gains have their own calculators and their own bills.
Honest numbers make better plans
The 6% default is a reasonable long-run assumption for a diversified portfolio before inflation, not a promise, and real returns arrive in lumps with some alarming years mixed in. Test your plan at 4% and see if it still works. Then aim the pot at something: the retirement age calculator turns savings into a date, and the ISA vs pension comparison settles which wrapper this money should live in first.
Common questions
How does compound growth work?
Each year of growth earns growth of its own, so a pot snowballs over time. The calculator applies your expected return to your starting amount and your regular contributions to project the future value.
What return should I assume?
There is no guaranteed figure, but a long-term real return of around 4 to 6% a year is a common, cautious assumption for a diversified stock-market portfolio. Lower assumptions are safer for planning.
Are investment gains taxed?
Inside an ISA, no: growth and withdrawals are tax-free, up to the £20,000 annual allowance. Held outside a tax wrapper, Capital Gains Tax and dividend tax can apply above their annual allowances.
These results are estimates for general information only and are not financial advice. Check every figure yourself and seek appropriate advice from a qualified professional before making any decision. Read the full disclaimer.