A retirement calculator is a tool that helps individuals estimate how much money they need to save for their retirement. It takes into account various factors such as age, income, expenses, inflation rates and expected returns on investments to provide an estimated amount of savings required by the individual to maintain their current lifestyle during their retired years. The calculator also helps in determining how much money needs to be set aside each month or year to achieve the desired retirement goal. It is a useful tool for individuals who want to plan and save effectively for their future financial security.