Wednesday 13 April 2016 3:09 pm

Alcohol guidelines are "inconsistent" and vary widely by country, scientists in the journal Addiction have found

What in the world constitutes a standard drink?

We've all had an over-enthusiastic bartender on a night out pour us a bit more than we would have expected, but scientists trying to work out what amount can be considered average have been just as baffled by the results as the rest of us. 

According to a new report by the scientific journal Addiction, the definition of a "standard" drink varies widely by country. Researchers surveyed 75 countries that might be expected to provide low-risk drinking guidelines and a definition of a standard drinking, but less than half (37 per cent) were found to do so, and the advice was surprisingly inconsistent. 

The researchers found the size of a standard drink varied by 250 per cent, from a low of 8g in Iceland and the United Kingdom to a high of 20g in Austria.

An 8g drink is equivalent to 250ml of four per cent beer, 76ml (2.57 oz) of 13 per cent wine, or 25ml (0.85 oz) of 40 per cent spirits.

In Chile, you can consume 56g of alcohol per day and still be considered a low-risk drinker. 

The World Health Organization (WHO) defines a standard drink as 10g of pure ethanol, with both men and women advised not to exceed two standard drinks per day. Although the WHO’s definition of a standard drink is the one most often used, 50 per cent of countries with drinking guidelines don’t use it.

Additional guidance also varied widely between countries, with Australia, Canada, Denmark, Fiji, France, Mexico, New Zealand, Poland and the UK all advising that you are allowed to drink more on special occasions.

Tired of the old double standard? In Australia, Grenada, Portugal, and South Africa, low-risk drinking guidelines are the same for women and men. The UK joined that list with its new guidelines in January. 

The UK unit guidelines were amended at the beginning of the year to 14 units per week for both men and women, while it was previously 14 units per week for women but 21 for men. 

While it might be slightly tricky to work out how much we should or shouldn't be drinking, the study's authors have urged us to take solace in the new research. 

"If you think your country should have a different definition of a standard drink or low-risk drinking, take heart – there’s probably another country that agrees with you," report co-author Keith Humphreys, said.