Compound Interest Calculator
Educational estimate · Not financial advice
Estimate how savings or investments may grow over time with a starting balance, monthly contribution, assumed return, and time horizon.
Enter your numbers and calculate.
How to use this calculator
Enter a starting amount, monthly contribution, assumed annual return, and time. Test conservative and optimistic scenarios.
Formula and assumptions
The calculator compounds monthly using the annual return divided by 12. It assumes steady contributions and a constant return.
Example
Saving $250 per month for 10 years can show how contributions plus compounding may grow over time, depending on the return assumption.
Limitations
- Investment returns are not guaranteed.
- Taxes, fees, and market volatility are not included.
- Savings-account APY and investment returns are different concepts.
This calculator is for general education only. It is not financial, legal, tax, credit, mortgage, or investment advice.
Related resources
Calculator FAQ
Are the results exact?
No. Results are estimates based on the inputs and simplified assumptions.
What should I do after calculating?
Use the result to compare scenarios, then verify current rates, fees, taxes, and terms before making decisions.