Defined benefit plans are flawed. a few years of double digit inflation after you retire will reduce them to a bread and water existence.The posted cpi rates and the actual will vary greatly in about 15-20 years. People on fixed income will suffer, due to the face that the system is somewhat broken.
I would say if you are 45 and need to retire today, you'll need about 1.5-2.5 million if you want to live till 85 without worrying.
I think the OP asked at 40 thought. I you do not have a million in assets by 40 you face a very restrictive life style after you retire.