For my own personal perspectives/needs, I have a simpler system that works for me. Just count the alcoholic content. For example, if I know my limit is 3 drinks per day, and that totals 250 units by ABV. That breaks down to (for example) 1 beer @ 5% ABV x 12 fluid ounces = 60; 1 glass wine @ 14% ABV x 5 ounces = 70; 1 martini @ 40% abv x 3 ounces = 120.
All 3 of these drinks total 250 units of alcohol. That is how I know I am at my limit and know that I can go to bed and not wake up with a headache the next day. Obviously if I have only 2 Jet Pilots or Zombies, that means I CANNOT have a 3rd, but if I am drinking beer, I could have a 4th beer with no worries, but a 4th glass of wine will put me at 280 and will put my body over the limit. 3 highballs will not. Again, I just add up the total ABV per ounce and keep it within +/- 3 and I know I will be fine and headache free the next day. Yes, it totally sucks to have to count those units while on vacation and/or at a party/celebration, but that’s the deal when you are in your 50s. In my 20s and early 30s that number was probably 700 or higher, but at this stage I know its 250 and with my formula, I never wake with a headache except maybe once or twice a year around the holidays when an especially generous host pours me way more than a standard 5 ounces of wine per glass and I did not refuse. It might not be exact science, but for my needs, it is, without too much math, formulas or variables.