You'll want to convert whatever amount still results in no tax liability, which seems like it might be around $10,620. Your decision will then be whether or not to convert more at a 10% marginal tax rate (or even a 12% marginal tax rate).
I usually consider whatever amount I convert now to be an amount I won't be distributing from my traditional retirement accounts at the tail-end of making distributions from the traditional accounts, so I consider what I expect my marginal tax rate to be then. I also consider that the earnings on an amount not converted now will be taxable instead of nontaxable when distributed at the tail end if not converted now. That does ignore the difference I'll have in future RMDs I'll have between converting now or not converting now, but I figure that difference is somewhat offset by being able to get more into Roth IRAs by converting more earlier instead of having to be distributed as RMDs.
I'm assuming that there would be no side-effects from an increase in AGI that would have a multiplying effect on your marginal tax rate such as an increase in the taxable amount of Social Security benefits. Also keep in mind that the 12% tax bracket is presently scheduled to go back to 15% in 2026.
