Compound Interest Calculator
Project a balance with an initial amount, monthly contributions and monthly compounding. See contributions and growth year by year.
Set your values
Adjust the values, then calculate your result.
How to use Compound Interest Calculator
- Enter your values or reset the included example.
- Review the settings and the format notes before continuing.
- Select Calculate, then inspect or copy the result.
Separate money contributed from hypothetical growth
Enter a starting balance, a regular monthly contribution, a fixed nominal annual rate and a period in years. Interest is applied monthly, then the contribution is added at the end of that month. The report separates the money you put in from the modeled growth and lists the balance at each year end. Currency selection affects formatting only and does not convert between currencies.
Understand the projection assumptions
A constant rate is a simplifying input, not a forecast or a promise. Real accounts and investments can have fees, taxes, changing returns, withdrawal rules and different compounding conventions. Inflation also changes what a future amount can buy. This calculator does not choose a product or recommend an allocation. Its bounded monthly simulation supports up to fifty years and rejects amounts outside the supported range; compare actual terms before relying on a financial projection.
Where is my calculation performed?
The calculation runs locally in your browser without a conversion API request.
Is input uploaded?
Processing takes place in your browser. This tool does not send your input or selected files to a conversion API.