Accumulating one million dollars by investing one thousand dollars each month depends heavily on the average annual rate of return generated by your portfolio. Assuming a historical annualized stock market return of roughly 8 to 10 percent with dividends reinvested, it typically takes approximately 25 to 28 years to reach the million-dollar milestone through consistent monthly compounding. Achieving this goal faster requires higher returns or larger monthly contributions, while lower returns will extend the required timeline.