This calculator models future investment portfolio growth using compound interest and recurring monthly dollar-cost averaging. It computes both nominal future balance and real purchasing power adjusted for expected price inflation.

### Mathematical Formula The future value combining lump-sum principal and periodic monthly contributions is evaluated as: $$FV = P \times (1 + r)^n + m \times \frac{(1 + r)^n - 1}{r}$$ Where $P$ is the initial investment, $m$ is the monthly contribution, $r$ is the monthly interest rate (annual return rate / 12), and $n$ is the total number of compounding months (years * 12). The inflation-adjusted real purchasing power is computed as: $$\text{Real Value} = \frac{FV}{(1 + \text{inflation})^{\text{years}}}$$

### Worked Numeric Example Investing an initial $10,000 plus $500 per month at an 8.0% annual return over 20 years (240 months): 1. Initial principal ($10,000) grows to $49,268.03. 2. Monthly contributions ($500/mo) accumulate to $294,510.21. 3. Combined Future Nominal Value equals $343,778.24 ($130,000 total cash contributed + $213,778.24 compound investment gains). 4. Factoring in a 3.0% annual inflation rate over 20 years, the real purchasing power of the portfolio equals $190,341.62.