While the Monthly Investment Calculator shows you an approximate returns rate, it also considers certain factors that may alter the expected rate of returns. These include: Inflation: The price of a commodity now will not be the same after ten years because of inflation. Market Volatility: The stock market is highly volatile. If the market underperforms, the rate of return would be lower than expected. Expense Ratio: If your monthly investments consist of Mutual Fund SIPs, the expense ratio of the fund manager will affect the return rate. Exit Load: If you decide to redeem your investments before maturity, the Asset Management Company will charge an exit load or a penalty for early liquidation.