Compound Interest Calculator
Model long-term growth from a lump sum plus monthly contributions with flexible compounding frequency.
Compound Interest Guide
What this calculator does
This calculator estimates how an investment can grow when interest compounds over time. It combines your starting principal with recurring monthly additions and shows the split between contributions and earned growth.
How to use it
Enter your principal, annual rate, number of years, and choose a compounding frequency. Add a monthly contribution if you want to model ongoing investing. The tool updates instantly so you can compare timelines and return assumptions.
Example usage
If you start with 50,000 and add 500 every month for 10 years at 8% annual return, compounding can contribute a meaningful share of the final amount. This makes the tool useful for savings plans, education goals, or general wealth projections.