Contributing to an IRA? Determine if you are eligible to contribute to a traditional or Roth IRA. You are viewing this website at a small screen resolution which doesn't support calculators. Click here to view this calculator. Share | Related Content The Rule of 72 Do you know how long it may take for your investments to double in value? The Rule of 72 is a quick way to figure it out. Required Reading: The Economic Report of the President The Economic Report of the President can help identify the forces driving — or dragging — the economy. Keys to Investing for Retirement There are some key concepts to understand when investing for retirement.