How to use this calculator
Explore a regular-investment scenario with monthly contributions, assumed price growth, dividends, tax and inflation. Results illustrate the assumptions you enter; asset labels and preset returns are scenario inputs rather than forecasts.
Monthly deposits stay monthly
Contributions are added at each month-end, regardless of the selected compounding frequency. Nominal annual price growth is converted to equivalent monthly growth. Enter annual return excluding any dividends that you also enter separately, so the same income is not counted twice.
The simplified tax setting reduces positive modeled gains and reinvested dividends. It does not assume a tax refund for losses or reproduce the tax treatment of a specific account. Turning off dividend reinvestment excludes that cash from the projected investment balance.
Separate purchasing power from investment gains
When inflation is enabled, the future-value display and chart show today’s purchasing power. Contributions, gains, the yearly breakdown and ROI remain nominal, so inflation is not mislabeled as an investment loss. ROI is the modeled gain divided by total contributed money; it is not an annualized return.
Constant returns do not represent real market paths. The model excludes fees, changing prices, withdrawals, tax allowances and differences between realized and unrealized gains. Try several assumptions rather than treating one ending balance as certain.
Example: contributions without growth
Starting with $1,000 and adding $100 each month for two years at 0% growth produces $3,400, with no nominal gain. At 10% annual inflation, its purchasing power is $3,400 ÷ 1.10², or $2,809.92 in today’s money.