Compound Interest Calculator
Estimate growth from a starting balance, monthly contributions, a fixed annual rate, and compounding frequency.
Data handling
Storage and export controls
- Retention
- The tool's working state is kept only while this page is open. Inputs and results are not saved to persistent storage by Got A Tool.
- Export
- The tool may prepare a result after you run it. It downloads or copies it only when you choose that action.
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How it works
Compound Interest Calculator: a practical guide
A compound interest calculator estimates how a starting balance could grow when a fixed annual rate is applied repeatedly and you make regular monthly contributions. It is useful for exploring a simple scenario before considering product terms, taxes, fees, inflation, and investment risk.
- STEP 01
Enter a starting balance and, if useful, a monthly contribution in the same currency units.
- STEP 02
Choose a fixed annual rate, a whole number of years, and how often interest compounds.
- STEP 03
Review the estimated balance, contributions, interest, and the annual table alongside the assumptions.
What this tool does and its limits
This tool simulates one month at a time. Interest is applied at the end of the selected period—monthly, quarterly, or annually—and the monthly contribution is then added at the end of every month. A fixed rate is an assumption, not a prediction. The result excludes taxes, account fees, inflation, deposits made on other schedules, withdrawals, losses, and any change in the rate. The estimate is not financial or investment advice.
Inputs, selected files, and results stay in your browser. The tool does not upload them to Got A Tool or save them to persistent storage.
Questions
Compound Interest Calculator details
Is the rate guaranteed?
No. The calculator keeps the rate fixed only so you can inspect one transparent scenario. Actual savings and investment returns can change or lose value.
When are monthly contributions added?
They are added at the end of each month, after any interest due in that month has been applied.
Why does compounding frequency change the result?
At the same stated annual rate, more frequent compounding applies interest to the balance sooner. The difference can grow over longer terms.
Does this include taxes or fees?
No. The estimate excludes taxes, account fees, inflation, withdrawals, and provider-specific rules.
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