How to work out your blood alcohol content

The latest in my ‘Learn Something New Every Day’ series – taken from The Great Courses’ Trails of Evidence: How Forensic Science Works (Lecture 33: Crimes – Nobody’s Supposed to Get Hurt)

Blood alcohol content (BAC) can be determined using the Widmark Formulat, thusly:

 (oz x %) x 5.14

lbs x .73

That is, multiply the ounces of alcohol you’ve consumed by the percentage of alcohol in the drink, and then multiply the result by 5.14. Then divide that number by the result of weight multiplied by .73 (for men) or .66 (for women).

Beer is typically 6% alcohol (.06)…. Wine is typically 12% alcohol (.12)…. Spirits – the % alcohol is half it’s proof.

So if I drank a full bottle of wine over four hours I’d be okay to drive in my jurisdiction….

Hmm… don’t think so.

The Widmark Formula works on the presumption that all the drinking is done at once (they must know me) and on an empty stomach (pfff, they don’t know me at all). To account for a longer, drawn out drinking session,  multiply the time elapsed since you started drinking by .015 and then subtract the result from your final Widmark BAC.

This is probably more useful for working out how long you need to wait after drinking until you are sober enough to drive. You know… if you weren’t too hammered to do the math.

(Bonus Something New:  Alcohol absorbs faster when mixed with carbonate beverages BUT people tend to drink slower when using a mixer.)