So now lets work bottom up: Housing (and Car) costsIf you live anywhere in the country other than directly in the middle of a major urban center then $3000 a month should be enough for rent and another $2000 for utilities, ... VacationI'm going to very generous here and say $48000 a year or $4000 a month for vacations. You can basically take a vacation a month (hey, you're retired so why not). And if your kids need an extra pair of shoes, take $100 out of your vacation ...