Compound Interest Calculator
See how your money grows over time with the power of compound interest. Daily, monthly or annual compounding with optional regular contributions.
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Changing currency changes the unit and formatting only; it does not convert the amounts.
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About this tool
What it does
Calculates compound interest growth using A = P(1 + r/n)^(nt). Supports daily, monthly, quarterly and annual compounding, optional monthly contributions and year-by-year growth breakdown.
Who it's for
Savers, investors and anyone planning their financial future. Used in the UK, US, Australia, Canada, Singapore, UAE, India and worldwide.
Your privacy
All calculations happen in your browser. No figures transmitted or stored anywhere.
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Frequently asked questions
What is compound interest?
Compound interest is growth on both the starting balance and previously accumulated interest. Results depend on the rate convention, compounding frequency, contribution timing, fees, tax and withdrawals.
What formula does this calculator use?
The starting balance uses A = P(1 + r/n)^(nt), with r as a nominal annual rate. Monthly contributions are added at the end of each month and use the monthly rate equivalent to the selected compounding frequency.
What is the Rule of 72?
The Rule of 72 is a rough mental estimate: divide 72 by an annual percentage return to estimate doubling time. It is only an approximation and is less accurate at very low or high rates.
How does compounding frequency affect growth?
For the same nominal annual rate, more frequent compounding produces a higher effective annual return. Do not use a quoted AER or APY as a nominal rate with a separate frequency, because AER/APY already reflects compounding.
What rate should I use?
Use a rate consistent with the scenario and its definition. For a deposit product quoted as AER or APY, use the Savings Calculator instead. Investment returns are uncertain, so test multiple scenarios rather than treating one rate as guaranteed.
How are monthly contributions timed?
The calculator assumes each contribution is deposited at the end of the month. Deposits made at the beginning of each month would earn slightly more because each contribution is invested for one additional month.