Compound Interest Calculator

The earlier and more frequently interest compounds, the larger the final balance. Regular deposits dramatically increase the long-term total.

Future value = P(1 + i)^N + D × [((1 + i)^N − 1) ÷ i], where i = rate ÷ frequency, N = frequency × years and D is the deposit per period. When i = 0 the deposits simply add up.

The projection assumes a constant return and ignores inflation, taxes and fees. Real returns fluctuate, so treat the result as an illustration rather than a guarantee.

10,000 at 8% compounded monthly for 10 years (no deposits) grows to about 22,196 — more than 2,196 above simple interest.

1. Enter your initial amount.
2. Add the annual rate, the number of years and how often it compounds.
3. Optionally add a deposit per compounding period.
4. Press Calculate.

• Entering the deposit per year when the period is monthly.
• Forgetting that real returns vary and are not guaranteed.

Compound interest earns interest on both your principal and the interest already added, accelerating growth over time. Add a regular deposit to model real saving.

Savers and investors who want to see how money grows over time, and anyone learning the power of compounding.

• Visualise long-term growth from a one-off or regular investment.
• See how compounding frequency affects the final balance.
• Separate your contributions from the interest earned.

• Projecting the growth of a savings account or deposit.
• Modelling regular contributions to an investment.
• Teaching the difference compounding makes over decades.