What is compound interest?
Growth earned on your savings plus on interest already added. Over time, compounding accelerates the total balance.
Compound Interest Calculator
See how your savings could grow with compound returns, a starting amount, and regular contributions over time.
Your savings
Final balance
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Total paid in
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Interest earned
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Breakdown
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Balance over time
Total balance compared with the cumulative amount you pay in.
Growth per year
Contributions you make each year compared with interest earned that year.
How this calculator works
The calculator projects your balance year by year using your starting amount, regular contributions, and an assumed annual return compounded monthly. Charts separate money you put in from growth earned.
Who this is for
Anyone exploring long-term UK savings — ISAs, general investment accounts, or pension pots in accumulation. Pair with the retirement planner for tax-aware pension modelling.
Assumptions
Returns are constant and gross of tax, charges and inflation. Real outcomes will vary. This is a planning illustration, not a forecast of investment performance.
Frequently asked questions
How much will I have if I save every month?
Enter deposits, return rate and years. The projection table and charts show the estimated end balance.
Does this include tax on savings interest?
No. Tax, fees and inflation are not included. Treat results as a simplified illustration.
How does this relate to retirement planning?
Use this for generic savings growth. For pension contributions and drawdown, use the retirement planner.
Important: Figures are indicative estimates based on the information you enter. Tax, charges, and inflation are not modelled. This tool is for planning and illustration only and does not constitute regulated financial, tax or investment advice.