It is also a good point to describe what is your targeted family situation as FIRE.
If you are planning to remain with no child, you will need less.
Another point will be to describe your place of fire. Being retired in France or Germany will require less.
So for my part, in the past 6 years we spend on average 45 kchf with my wife.I estimate we’ll need 50k chf.
My estimation will be 1,4 m chf with a safe withdrawing rate of 3,75% for a family of 3 in France (except Paris). I will keep an occupation to generate 10 keur a year or my wife will be working ( to avoid puma).
Maybe a bit more because I am including 2nd pilar and I have currently less than 50% in stock.