The amount in box 1 of your W-2 minus any amount in box 11 is compensation that will support a traditional IRA contribution. Otherwise, the amount that you contribute to a 401(k) or a 457(b) is not a factor in determining the amount that you are eligible to contribute to a traditional IRA. (If you defer all of your available compensation to to the traditional 401(k) and the 457(b) accounts, there would be a zero in box 1 of your W-2.)
There is no limit on the amount that you are eligible to convert to Roth.
