Where will your retirement income come from? Some from Social Security, probably. And some from a 401(k) or other type of employer-sponsored plan. But many Americans also have Individual Retirement Accounts. There are two major types: a Traditional IRA and a Roth IRA. Steady contributions to either type can help you build a sizable portfolio. But the accounts have their own unique tax advantages. This calculator might help you figure out whether a Roth or a Traditional IRA might best suit you.