Compound Interest Calculator
Estimate compound growth with contributions, scenarios, a chart, and yearly table.
How does compound interest work?
Compound interest adds each period's interest to the balance, so the next period earns interest on the interest as well as on the original amount.
Formula: Balance compounds at the selected frequency: A = P(1 + r/n)^(nt), with contributions added throughout each year.
What this calculator does
Project a starting balance with recurring contributions and selectable compounding frequency, then compare growth scenarios.
Use it to turn Starting amount, Annual interest rate, Years, Monthly contribution, and the other shown inputs into a checked result you can compare, copy, or rerun with different assumptions.
The page shows the formula, a numeric worked example, and the assumptions that affect this finance calculation.
Inputs and what they mean
- Starting amount
- — number value.
- Annual interest rate
- — number value.
- Years
- — number value.
- Monthly contribution
- — number value.
- Compounding frequency
- — choice value.
How to use it
- Enter the starting amount and annual rate.
- Set the term, monthly contribution, and compounding frequency.
- Review the estimate, scenarios, yearly table, and chart.
Formula
Balance compounds at the selected frequency: A = P(1 + r/n)^(nt), with contributions added throughout each year.
Inputs used: Starting amount, Annual interest rate, Years, Monthly contribution, Compounding frequency.
Edge handling: Starting amount is required.; Starting amount cannot be negative.; Starting amount must be no more than 1000000000000.; Annual interest rate is required.; Annual interest rate cannot be negative..
Worked example
$10,000 at 6% for 10 years
- Start with Starting amount: 10000, Annual interest rate: 6, Years: 10, Monthly contribution: 100, Compounding frequency: 12.
- Apply the method: Balance compounds at the selected frequency: A = P(1 + r/n)^(nt), with contributions added throughout each year.
- Add $100 monthly to compare contributions with estimated compound growth.
Reading the result
The headline figure is the main answer. Any breakdown underneath shows the parts that make it up, so you can check the working and see what changes when you adjust an input.
Limitations and assumptions
- Inputs outside the supported range are rejected rather than forced into a result.
- The result depends on the values you enter for this compound interest calculator; it does not supply missing rates, rules, prices, dates, or assumptions for you.
Common questions
How does compound interest work?
Compound interest adds each period's interest to the balance, so the next period earns interest on the interest as well as on the original amount. Check the formula, example, and limitations on this page before using the result for a real finance decision.
Is the result guaranteed?
No. It is an illustration based on a constant rate and does not predict investment performance.
When are contributions added?
Monthly contributions are spread across the selected compounding periods for a practical estimate. Check the formula, example, and limitations on this page before using the result for a real finance decision.
How do I use the Compound Interest Calculator?
Enter the required values for Starting amount, Annual interest rate, Years, Monthly contribution, Compounding frequency. The calculator applies the formula on this page and shows the main result with any supporting breakdown so you can check the arithmetic.
What formula does the Compound Interest Calculator use?
Balance compounds at the selected frequency: A = P(1 + r/n)^(nt), with contributions added throughout each year. The visible formula section above lists the calculation path and the edge cases the page handles, so the result can be checked without relying on the form alone.
Can the Compound Interest Calculator be used for exact decisions?
Use it as a calculation aid, not as a substitute for checking the underlying rule, contract, policy, or professional advice that applies to your situation. When a result depends on local rules, personal details, prices, or dates, enter those values yourself and confirm them before acting.
Cite this page
Free Calculator. (n.d.). Compound Interest Calculator. https://freecalculator.tech/tools/compound-interest-calculator
"Compound Interest Calculator." Free Calculator, https://freecalculator.tech/tools/compound-interest-calculator.
Compound Interest Calculator — Free Calculator, https://freecalculator.tech/tools/compound-interest-calculator
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