"Yet New Zealanders aren't provided with information of standard drinks in many bars and pubs."
According to the Health Promotion Agency, a 100ml glass of a 12.5 per cent wine was equivalent to 1 standard drink.
Therefore, a 250ml pour equated to 2.5 standard drinks, and exactly a third of a bottle of wine.
Even when consumed over a two-hour period, that amount could also tip most women over the alcohol limit for driving, according to Hospitality NZ.
Jackson said Ireland had last month passed a law to require pubs and bars to provide consumers with information on the amount of alcohol in each glass sold.
"New Zealand needs to follow suit."
In most cases, on bar and restaurant menus, the price of the larger serving option fell just under double the price of the smaller pour, making it similar value-wise for 150ml and 250ml respectively.
A small glass of SOHO Bobby Pinot Noir at Uptown Freehouse in Eden Terrace was $10, and a larger pour $17.
Down the road at Countdown, the whole bottle could be purchased for $18.99. Manager Brenton Dix said the variation was about giving drinkers an option.
"We've got a lot of media people coming in here, a lot of businesses and they like their wine."
Larger servings went well on Fridays, he said, whereas he noted more patrons opting for a smaller pour during the week.
If someone seemed to be overdoing it, Dix said a staffer would keep tabs, and make sure they weren't driving. Very few people questioned how many standard drinks were in a glass, he said.
A similar pattern could be found at Auckland Central bar Vikki Lane, where you could order a 150ml pour of wine or a larger 250ml tipple.
Customer Stacey Hunt, who had opted for a small rose, said it would be useful for bars to include a guide on how many standard drinks were likely in each pour.
"Particularly if you're driving, it would be good to know if you should go for a big one or a small one."
Co-owner David Robinson said the bar had actually scaled back its size varieties - the menu used to offer a 50ml glass allowing people to taste a wine "without getting legless".
It was useful to offer the variety to people out for different occasions, he said.
Kim Odendaal, Hospitality New Zealand regional manager, said many venues offered different size pours to provide choice and cater to their patron's needs.
The trend had been around for several years, she said.
While a "standard" pour of wine was commonly 150ml, there were no specific restrictions on how much alcohol a small or large glass held.
"One patron may prefer enjoying a beverage over a longer period of time, so that they don't have to get up and reorder, and there are less interruptions to their conversation with friends or family," she said,
"Another person may prefer a smaller glass, because they are short on time that day, or have another engagement to attend."
Larger glasses also allowed the wine to breathe, she pointed out.
From a practical point of view, venues might prefer larger pours to reduce the amount of glassware needed, or reduce cleaning costs.
Hospitality NZ's 'Rule of Thumb' guidelines
• Studies suggest that men can consume three standard drinks over two hours and still be on the right side of the legal 250mcg breath alcohol drink-drive limit.
• Women can enjoy two standard drinks over a two-hour period.
• In the case of beer, a standard drink equates to: a 500ml glass of 2.5 per cent alcohol-by-volume (ABV), a 330ml stubbie of 4 per cent ABVbeer, or a 250ml glass of 5 per cent ABV beer.
• A 100ml glass of a 12.5 per cent wine is equivalent to 1 standard drink.
• If people are in any doubt, then it is best not to drink at all before driving.
