Compound Interest Calculator
Model how a one-time deposit (and optional recurring annual contributions) grow over time with compound interest. Adjust the principal, annual rate, compounding frequency and time horizon to see your final balance, total interest earned and a year-by-year growth chart.
How to use
- 1
Enter the principal
Type the lump sum you are starting with. Defaults to 10,000 so the chart is immediately useful.
- 2
Set the annual rate
Enter the nominal annual interest rate as a percentage. For a savings account paying 4.5%, type 4.5.
- 3
Pick compounding frequency
Choose how often interest is credited — daily, weekly, monthly, quarterly, semi-annually or annually. More frequent compounding earns slightly more interest.
- 4
Add the time horizon and contributions
Enter the number of years and an optional annual contribution. The chart and totals update live.
Common use cases
- Project the growth of a fixed deposit or high-yield savings account.
- Compare monthly vs annual compounding on the same nominal rate.
- Model a recurring annual investment in a long-term savings goal.
- Show the long-term impact of starting to invest 10 years earlier.
Limitations
- This calculator produces an estimate only and is not professional financial, tax or investment advice. Always confirm the underlying formulae with your accountant, bank or financial advisor before making decisions.
- The model assumes a constant interest rate for the full horizon. Real returns fluctuate year to year.
- Contributions are added evenly across each year; interest is credited per period using the nominal annual rate ÷ periods.
- Inflation, taxes on interest and fees are not modelled. Adjust the rate downwards to approximate real (after-inflation) growth.
Frequently asked questions
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