What this example shows
This scenario isolates the math behind a one-time investment left to compound. The ending balance reflects both money contributed and the compounding effect of leaving prior gains invested.
Because the same assumed return is applied every month, the path is smoother than real markets. The point of the example is to show sensitivity to contribution size, starting balance, return assumptions, and time horizon.
Because the full amount is invested immediately, this scenario carries more sequence-of-returns risk than a plan that phases money in over time.
Assumptions and limitations
The example assumes no additional contributions, full reinvestment, and a constant 7% annual return with monthly compounding. It does not include taxes, fees, inflation, or periods of negative returns.
That makes the page useful for planning and comparison, not prediction. Real portfolios move unevenly, and the amount actually available to spend can differ materially from the projected balance.
How investors use a page like this
Use the result as a benchmark, then test conservative and optimistic cases in the main calculator. Changing one assumption at a time makes it easier to see whether starting balance, contribution rate, or time horizon matters most for your plan.
For account decisions, also compare taxes, inflation, and fees. A larger nominal balance is not automatically a better outcome if the strategy requires more risk, has higher drag, or produces less after-tax purchasing power.