This compound interest calculator assists in two core planning tasks: estimating portfolio growth or finding the exact yield needed to reach a specific financial goal.
1. The Power of Compounding
Exponential growth happens because the interest in each period is earned not just on the principal, but also on the accumulated interest from past periods. It's the "snowball" effect.
2. Future Value Mode
The classic formulation. Input your starting balance, how much you can contribute monthly, a conservative rate estimate, and your time horizon. The tool projects your final portfolio value.
3. Required Rate Mode
If you have a defined target (e.g., $1M for retirement), this feature reverse-engineers the exact portfolio return you must achieve in the market to make the math work with your current contributions.