BAC calculator not working

I drank a 750ml bottle of scotch (43%abv) earlier and became quite drunk. I’m pretty much completely sober now but decided to put in my info into a BAC calculator and it says my BAC was 0.4??? This is the first time I’ve drank anything other than beer and I had not eaten before so there is no way in hell my bac was 0.4. I was wondering if I input something in wrong.

https://www.calculator.net/bac-calculator.html