HALP!! BAC Calculation

I need a factual answer and fast please please please (this is for an anti drink drive article in a magazine)

I know that alcohol is metablised at the rate of 0.015% BAC per hour
I also know that one standard drink = 0.02% BAC

The legal limit is 35 microgrammes of alcohol per 100 millitres of breath, or more than 80 milligrammes of alcohol per 100 millitres of blood.

So my question is - how do I convert from BAC to microgrammes / milligrammes per litre?

The intent of the question? Tell people how long they have to wait once they go over the limit, and how quickly they will get to the limit

I think any kind of even rough metric that is “Amount of alcohol ==> BAC” is not very useful at all. If you want a usable average try finding some sort of an average “Amount of alcohol/pound of body weight ==> BAC” table.

I have found that - I have all the tables I need, but they are in BAC - I just don’t know how to get from BAC to microgrammes per milli-litre

I am reasonably competent at math, and if I can get a straight forward formula I can do the math - just need a clear formula

1% BAC = 1/100 (%) g/mL = 1 cg/mL which would be 10,000 micrograms per ml.


Thanks man

Hugely appreciated - I can work it out from here

Double post…

That’s not quite right. You’re comparing mass and volume. 1% would be 10,000 micrograms per gram, not mL. You need to factor in for the density of blood.

Edit: Thinking about it though, it would be really close since blood is mostly water and the density of water is 1 g/mL. So depending on how accurate it needs to be, I guess this might work.