Since a Roth conversion is a taxable event (in other words, you will have to pay taxes on the amount of money you are converting), when determining how much to convert, you may want to consider how much money you have set aside in nonretirement sources to pay the resulting taxes. You may also want to consider converting to a Roth IRA over a number of years (tax periods) in amounts that will keep the income from the conversion within your current federal tax bracket, or within a federal tax bracket you are comfortable with.