Experimenting with a Breathalyzer

This is what I’m doing this week (I’m updating this story as I go):

5-day observational experiment to see how much fluctuation occurs with my alcohol metabolism, estimated by a breathalyzer. This is the first of a series of experiments:


  • BACTrack Select Breathalyzer S80: Breathalyzers aren’t that accurate. This machine claims to have sensor accuracy of +/-0.01 at 0.05% BAC, so not that great. If I could do blood tests at home, I would but for now, I’ll use this.
  • Fremont Brewery Lush IPA 7% ABV
  • Trustworthy friend(s)


1. Drink Fremont Brewery Lush IPA over 30 minutes (8:40–9:10PM). Gotta have something tasty if I’m going to have the same drink every day.

2. Ask a trustworthy friend (Benjamin Mako Hill this time) to measure BAC on the breathalyzer at 20, 30, 40, 50, 60, 80 and 120 minutes. Two measurements at each time point. No food or drinks 20 minutes before measurement (meaning no food between 9:10 and 10:10PM and between 10:50 and 11:10PM. I will not look at the results until after the last measurement on the last day (11:05PM on Friday) to avoid behavioral change. I just want to know my “usual” within-person variation. (NOTE: I changed this to 20, 50, 80, and 120 after my trustworthy friend told me on Day 1 that this many points are probably not necessary.)

3. Write down the max/min temperature of the day, my weight, diet, liquid intake, and physical activity.

I tried hard not to change any of my behaviors other than my drinking because the point of this experiment is to understand my “normal” fluctuation.

One inconvenience is that I can’t eat or drink for 20 minutes before measurement. Since we eat communally, the timing may not work out. We usually eat sometime between 10 and 11, so I’m hoping this will work out.

Will write about the results when I find out on Friday night.


Update (Day 3): I should’ve written down my hypothesis before I started my experiment. My hypothesis after the first measurement on Day 3 is: my within-person fluctuation for the first measurement each day is +/-0.01 on this machine. I also believe that +/- 30 minutes for reaching 0.01. Also, BAC may get higher on hotter days when I’m more dehydrated.