Jack Tools

Compound Interest Calculator

Estimate how your savings or investments could grow over time with compound interest and regular contributions.

Enter your details

£
£
%
yrs

This calculator is an estimate only and does not include tax, inflation, platform fees, fund charges, or investment risk.

Estimated future value
£0.00
Interest earned: £0.00
Total invested
£0.00
Interest earned
£0.00
Initial amount
£0.00
Monthly contribution
£0.00

Growth breakdown

Annual interest rate 0%
Investment period 0 years
Compounding frequency Monthly
Total contributions £0.00

How This Compound Interest Calculator Works

This compound interest calculator estimates how savings or investments could grow over time when interest is earned on both the original amount and on previous growth.

The calculation uses your starting balance, regular monthly contributions, annual interest rate, investment period, and compounding frequency to project a future value.

Compound growth can become more powerful over longer periods because each period’s return is added to the balance before the next period’s return is calculated.

This makes the tool useful for comparing long-term savings plans, investment contributions, and the effect of starting earlier rather than later.

Initial investment The starting balance of your savings or investment before any future growth or contributions.
Monthly contributions Regular deposits added each month to increase the total amount invested over time.
Interest rate The annual return or interest rate used to estimate growth.
Investment period The number of years your money remains invested or saved.
Back to calculator ↑

Example Compound Interest Scenarios

£10k investment
Monthly£250
Rate7%
Years20
Large long-term growth
£5k investment
Monthly£100
Rate6%
Years15
Steady growth over time
£25k investment
Monthly£300
Rate5%
Years10
Balanced growth projection
£50k investment
Monthly£0
Rate4%
Years25
Pure compound growth

Compound Interest Calculator FAQs

Compound interest is interest or investment growth earned not only on the original amount but also on the growth that has already built up over time.
Over longer periods, compounding can significantly increase growth because returns continue to generate additional returns, especially when regular contributions are added.
Compounding frequency depends on the type of account or investment. Some savings accounts compound monthly or daily, while some investment projections use annual growth assumptions.
No. This calculator estimates nominal growth only and does not adjust for inflation, tax, charges, or investment platform fees.
Yes. Even relatively small regular contributions can have a large long-term effect because each contribution also has time to compound and earn additional growth.
No. The result is only an estimate based on the figures you enter. Real savings and investment returns can vary and may be lower or higher than the projected amount.

Related tools

Savings Calculator Project savings growth with regular contributions. Inflation Calculator See how inflation can affect future buying power. ROI Calculator Measure returns on an investment more directly.