IRA withdrawal

I am required to withdrawal some money from my IRA retirement account this year. How do I calculate how much I can take out without being put into another tax bracket? This is that only year I get to file as a joint return (wife passed) and think it would be better to withdraw as much as I can from the IRA this year. P.S. I barely get by with monthly income and I don’t have a lot in the IRA account.