Investment Calculator
Project the future value of an investment with an initial amount, monthly contributions, rate of return, and compounding.
About the Investment Calculator
Long-term investment growth depends on three levers: how much you start with, how much you add along the way, and the rate of return you earn. This calculator combines all three to project a future value, showing how much of the ending balance came from your own contributions versus market growth.
How It Works
Starting from your initial investment, the calculator compounds the balance at your expected annual return using the compounding frequency you choose, adding your monthly contribution each month. It tracks the running total separately from contributions, so the difference between the final balance and total contributions shows exactly how much growth your money generated.
Balance compounds each period at rate/frequency, with monthly contributions added; Growth = Final Balance − Total Contributions.
Example
Scenario: $5,000 to start, adding $300 monthly, at an 8% expected annual return, over 20 years.
Result: Projected future value of about $186,700, of which roughly $77,000 is contributions and $109,700 is investment growth.
Assumptions & Limitations
- Assumes a constant average annual return, which real markets never deliver in a straight line year to year.
- Contributions are assumed to be made every month without interruption.
- Does not model market volatility, sequence-of-returns risk, taxes, or fund fees, all of which affect real outcomes.
- A single average return is a simplification useful for planning, not a guarantee.