How to decide the magic FIRE number?

[Hemant]

I've been lurking in this sub for a while and I'm wondering—how do you forecast inflation, medical expenses, kids' higher studies, longevity, etc.? Where should I start? Any books or resources I can refer to learn more? Are there any formulas? TIA

[Chiranjit]

https://fiindia.gitbook.io/wiki/

[Rajat]

There are plenty of online calculators. As a rule of thumb, aim for about 35‑50 times your first‑year retirement expenses.

[Jayant]

Did you not even lurk through the wiki?

Or are you expecting everyone to spoon‑feed you the formulas?

[Shivendra]

When my passive income exceeds the amount I need for a healthy, comfortable lifestyle.

In my case, a passive income of USD 39,000 from my dividend portfolio lets me FIRE whenever I choose.