Define FIRE

[ACyclist]

Is that when your investments earn the amount of your living expenses? 

How do you know when you can fire?

[MDM]

See Safe withdrawal rates and Stop worrying about the 4% rule for some background.

[Dicey]

Thanks MDM. All done.

[Bateaux]

I'm more confused than ever.  Going to work tomorrow and again till it reveals itself.

[Linea_Norway]

Is that when your investments earn the amount of your living expenses? 

How do you know when you can fire?

You know you can FIRE when taking out 4% (or less) from your investments covers your yearly expenses.

If you want to FIRE, but your 4% investments do not cover quite enough yet, you could consider keeping a part time job or doing a side-gig to make up for the difference. Or spend less.