The State of Maryland, in conjunction with the Mothers Against Drunk Driving, has released a very clever new smartphone app, which monitors your alcohol consumption.
The ENDUI App, takes initial information about your gender and weight, and then plots your drinks as you have them to approximate your "absorption-elimination curve." If you input that you just drank one beer, it will wait for a few minutes--the amount of time for the alcohol to reach your bloodstream, and then register .01 as shown to the left.
If you keep drinking, (and input the number of drinks), it will apply well-accepted estimates of alcohol absorption and elimination to give you a rough idea of your blood alcohol. Or rather, what level of blood alcohol an average person of your weight and gender would have with the number of drinks you have input.
It's kind of fun to play with, and probably worth downloading if you ever drive after a drink or two. But you must remember the old adage, "Garbage in-garbage out." The app only estimates where the average person would be, and not what your exact blood alcohol level is. It doesn't take into account particulars like when you ate, and what and how much you ate, which can strongly affect your blood alcohol level.
The app can be downloaded for the iPhone here: https://appsto.re/us/FZAk2.i
It is also available for Android devices through Google Play.