It’s hard to predict the effects of alcohol accurately.
You can’t really know in advance what effects 1, 2, or 3 drinks will have on you. It depends on several factors:
Who are you?
The effects of alcohol differ depending on your height, weight, health, psychological state, and experience with drinking.
What did you drink?
The effects differ depending on the amount, the percentage of alcohol the product contains, cocktails mixed with different kinds of alcohol or with other substances (medications, drugs), how fast you drink, and what you ate (or didn’t eat) during the day.
What context are you drinking in?
The reasons why you’re drinking, the mood, the time of day, and the place are all factors that can cause the effects of alcohol to vary.