Irrespective of local driving laws relating to alcohol its important to note that having any alcohol at all in your bloodstream generally invalidates your car rental insurance. Therefore, my advice is avoid drinking at all if you plan to drive, irrespective of local drink drive limits. Its often tempting especially if you’re staying in a remote location and roads to the nearest village are quiet but, especially at night, these roads can be the most dangerous. At best you may be forced into paying a large amount of compensation or ‘hush money’ to local police or the other party involved in an accident. At worst you could be facing a long jail term in a foreign prison. Not worth the risk in my opinion.

Blood alcohol content is the method of measuring intoxication in most parts of the world. This is basically the percentage of a persons blood which is alcohol. For instance, a drink drive limit of BAC of 0.10 means that 0.10 (one tenth of one percent) of a person’s blood, by volume, is alcohol.

The level at which alcoholic drinks consumed affect BAC depends on a number of factors – the type and quantity of drink consumer, the weight of the person consuming the drink, and how long they take to drink it.( Contrary to popular opinion, its now thought incorrect that alcohol has less of an effect on men than women, and both sexes generally transfer drinks to BAC at roughly the same rate.) There are a number of online calculators which help you work out your approximate BAC . These work on fluid ounces of alcohol consumed – Note that the benchmarks used are for half a pint of beer and a small (120ML) glass of wine.

https://www.alcohol.org/bac-calculator/

Once you understand your likely BAC, the legal used as the drink drive limit varies by country as shown in the table below. (Some countries also use roadside tests for Breath Alcohol limit, but the definitive test will still likely be Blood Alcohol Content).

Drink Drive Limits by Country

Source- World Health Organisation Oct 2018