Smart Investor's Calculator (SIC) allows users to find optimal investment portfolios through solving allocation problems with the selected criterion and restrictions on shares of investment in each instrument\group. In other words, SIC helps investors to find investment portfolios that, maximize returns and limit risks. A user may choose to maximize a pre-tax or post-tax rate of return on a portfolio, subject to restrictions, which reduce the risks. The user may edit, add and navigate the investment data.