BAC / tolerance question

I just drank a 1 liter bottle of Fireball (33%) in about 3 hours. Out of curiosity I checked a couple BAC calculators, both claiming I have a BAC that would likely put me in a coma and/or kill me (above 0,4). I don’t feel sick at all – I’m a bit drunk but I feel fine. I do drink regularly, but is tolerance really this significant or are BAC calculators just incredibly inaccurate?

I have been to the hospital once for alcohol poisoning and/or likely being drugged (somewhat unclear what made me sick, my BAC was 0,18 and by my standards I hadn’t drank very much), if that’s helpful.