You should have a 1099R for that.  What code is in box 7?  When you enter it in Turbo Tax it will ask you what you did with it.  

I don't think there is a limit on how much you can convert.  This is not a new ROTH IRA contribution. So don't enter it under Deductions.  Only enter the 1099R.  @dmertz  

Oh I forgot to tell you where.

The easiest way to get to the 1099-R entry screen is to simply search for 1099-R (upper- or lower-case, with or without the dash) in your TurboTax program and then click the "Jump to" link in the search results.

Enter a 1099R under

Federal Taxes on the left side

Wages & Income at the top

Then scroll way down to Retirement Plans and Social Security,

Then IRA, 401(k), Pension Plans (1099R) - click Start or Revisit

If you are filing a Joint return be sure to pick which person it is for.

You can convert as little or as much as you want, limited only by your tolerance for the increase in your tax liability for the year of the conversion.

The program does not offer an option to convert to a Roth

Yes, there is a way if you follow these instructions.

• log in to your Turbo Tax account
• click on "take me to my return"
• click on the "federal taxes" tab
• click on "wages and income"
• choose "show more and "see list of all income"
• scroll down to "retirement plans and social security"
• click on "start" next to "IRAs, 401(k), etc"
• enter the information for your 1099R
• Turbo Tax will ask you questions about your Traditional IRA distribution
• When you reach the screen that says, "what did you do with the money?", choose the option that says, "I moved the money to another retirement account"
• After you choose this option, another set of options will appear:
• If you converted the entire distribution to a Roth IRA, choose "I converted all of this money to a Roth IRA"
• If you only converted some of the distribution to a Roth IRA, choose, "I did a combination of rolling over, converting, and cashing out the money." If you choose this option, Turbo Tax will ask you to identify how much of the distribution was converted to a Roth IRA, and how much of the distribution was rolled over into another retirement plan.
• Next you will the screen that says, "your 1099R entries". Scroll down to the bottom of the page and click "continue". Turbo Tax will ask you more questions and you will need your 5498 Form for your Traditional IRA. A year end statement might also provide the necessary information.