I'm confused by all the comments about "we spend XXX.....not including taxes, health costs, housing, and whatever." To me, the only true measure of expenses is what you spend - and that includes housing, health, taxes and anything else that passes from your hands to someone else. If all your outgo comes to $100K a year, you don't get to subtract items that you don't think are expenses. If it goes out the door, then it's an expense and part of your budget. Savings by any means are not part of expenses.
In our case, fixed gross income after retirement (for a 2 earner family) is 50% lower than what it was prior to retirement. Post retirement income includes pensions and SS. However, our expenses prior to retirement - meaning the money wasn't readily available to us anymore including savings - were 100% of our income. This includes normal expenses, taxes, 401Ks, IRAs, I bonds, etc., etc. The only way it can be different for anyone is if they spend more than they earn through use of credit (which many do - maybe not on this list, but in the general population.
Our post retirement expenses are equal - just about 100% - to those of pre-retirement, just in different categories. A LOT more spent on travel (many trips by land and sea to exotic places around the world - we are away from home about 50% of the year). Nothing spent on savings, SS, pension costs, etc. This means that, for a few years, we will be drawing far more than 4% from our savings. It's unlikely we can continue at this pace for any length of time - for both physical and economic reasons, but it's a lot better to do things you want to do while you are able to, rather than wait until you are older and can't. We are lucky in that our income from other than withdrawals from savings will pretty much cover all our outgo once we ramp down on the trips in a few years. RMDs will also force us to keep traveling
. After we stop, we can enjoy the over 100K digital jpgs, mpegs, etc. we are accumulating. That's what we worked for - not about to sit around and wait to grow older counting pennies.