It is a busy Wednesday lunchtime at city eatery Cookie when a pretty waitress walks to the table with a bottle of Dragonfly Willow Bridge shiraz.
She proceeds to pour a glass of the $9-a-pop Western Australian red. It is a generous glass. But just how much wine it contains is anyone's guess.
That's until we pull out a standard measuring jug and empty the contents of the glass. There is exactly 190ml.
Anyone who has been to a bar or restaurant and ordered wine by the glass knows that how much, or how little, you get often depends on the generosity of the venue, or in some cases, how sweetly you smile at the bartender.
As Fairfax Media discovered recently during a survey of Melbourne restaurant and bars, a glass of wine at one venue can be poured liberally to the brim while at another you could swear the the waiter took a swig on the way out to the table.
Of course, trying to figure out exactly how much wine you are getting is complicated by the fact different-sized wine glasses are used at different venues and depending on the variety of wine.
"A glass of wine is one of the few items that you purchase that you really don't know what you're getting for your money – what quantity you're getting," says Consumers' Federation of Australia's John Furbank.
"I mean you wouldn't go to a supermarket and buy some vegetables if you didn't know how much you were going to get for your money, would you?"
In the past fortnight, Fairfax Media set out to find out exactly how much was in a glass of wine and how big these perceived discrepancies in by-the-glass wine servings are.
We visited 10 venues – chosen randomly – and ordered a glass of the house (or the cheapest) shiraz, which ranged in price from $7 to $11. The wine servings were measured using a standard measuring jug.
We found by-the-glass wine servings varied between 145ml and 190ml – depending on the establishment.
Mr Furbank says he is not surprised there were differences of up to 45ml and says a broader sample would have found even greater discrepancies.
Fine-dining restaurant Cutler & Co. in Fitzroy, for example, serves its wine by the glass to just 120ml. It does, however, disclose its serving sizes on its wine list. Until very recently, Circa in St Kilda, which also lists its serving sizes on its wine list, poured just 100ml per glass. It has increased that to 150ml.
Mr Furbank argues it should be mandatory for all Australian bars and restaurants to serve unpackaged wine in "standardised" wine glasses to prevent such large discrepancies.
By "standardised", he means using wine glasses of any size so long as they have a clear pour line, known as a plimsoll line, which marks a specific measured amount.
"We've recommended that line be at 150ml because that seems to be the unofficial industry standard anyway, even though it isn't always poured accurately," says Mr Furbank.
Four of the venues visited by Fairfax Media did have obvious plimsoll lines on their wine glasses – measuring at 150ml. This did not always ensure we received 150ml of wine.
Transport Bar in Federation Square confirmed their plimsoll line measured 150 millilitres. Despite that, the $10-a-glass shiraz we ordered was poured just above the plimsoll line and measured 160ml.
The other three venues that used plimsoll lines – including The Bridge Hotel in Richmond, Bridie O'Reilly's in Chapel Street, and Cafe L'incontro in Swanston Street – all poured to the line at 150ml.
Another four establishments had their business logo or "badge" printed on the glass, which staff appeared to use as a pour line.
A spokesman for The Carlton in Bourke Street confirmed it used the badge, rather than a plimsoll line, because it was "less ugly", to measure 150ml per glass. Despite this we received a 160-millilitre glass.
At Saigon Rose in Prahran, which also served in badged wine glasses, we received 170ml of the $9-a-glass Grant Burge "The Vigneron" shiraz, which was poured well above the badge.
The two eateries that did not have plimsoll lines or badges on their glasses poured the biggest and the smallest servings of the 10 eateries.
The 190ml of shiraz we received at Cookie came in a glass with no plimsoll line or badge. Meanwhile, at Prahran restaurant Patee Thai, which also uses glasses without plimsoll lines, we were served just 145ml of the $7 McWilliams house shiraz.
Consumer groups are not only concerned that consumers do not know exactly how much wine they are getting for their money, but how many standard drinks they are consuming for those concerned about drinking responsibly and their ability to drive.
Currently, under the National Trade Measurement legislation, wine – unless it is pre-packaged, such as in a bottle or cask – does not have to be sold by a volume measure.
However, in 2010, Australia's peak measurement body, the National Measurement Institute, published a consultation paper proposing that the legislation be extended to the sale of unpackaged wine.
It proposed that the sale of wine when not pre-packed, including wine by the glass, be served "in containers marked with a line (plimsoll line) indicating 150ml and/or 180ml where sold by the glass".
In the consultation paper, the NMI states: "there has been an increase in consumption of alcohol by the glass ... Consequently, the discrepancy in the quantity dispensed by the same and/or different establishments has become more of a concern".
The NMI told Fairfax Media this week "a legislative response in relation to this issue remains under consideration" and that feedback on the 2010 consultation paper "received a mix of responses".
The Australian Hotels Association has consistently opposed calls for mandatory plimsoll lines. In its 2010 submission to the NMI it said the proposal would "impose a significant cost burden on every licensee as new glassware would need to be purchased containing the required plimsoll lines".
CHOICE disagrees. It says mandatory plimsoll lines would ensure a "level of consistency in serve sizes so that consumers can compare value for money" and help consumers to "monitor their alcohol consumption to meet blood-alcohol limits".
According to the federal government's standard drink guidelines, 100ml of 13 per cent alcohol red wine is equivalent to one standard drink, while 100ml of 11.5 per cent alcohol white wine is approximately 0.9 standard drinks.
Safe drinking advice suggests that to stay below the 0.05 legal blood-alcohol limit, males can drink no more than two standard alcoholic drinks in the first hour, followed by one standard alcoholic drink every hour after that. Females can drink no more than one standard alcoholic drink every hour.
CHOICE has suggested there be mandatory plimsoll lines at 150ml and 200ml so that consumers could better "monitor their alcohol consumption for health and driver safety reasons".
For example, a 150ml glass would be roughly equivalent to 1.5 standards drinks, and a 200ml glass would be roughly equivalent to two standard drinks.
Sally Humble, sommelier at St Kilda's Circa at The Prince admits it is a problematic issue, but says it should be up to each venue to determine how much wine they choose to serve per glass.
She says a better solution would be to make it compulsory for all venues to print their by-the-glass serving sizes on their wine list, as Circa does, so consumers know exactly how much they are getting for their money.
Its wine list notes that by-the-glass red and white wines are served at 150ml, sake at 100ml, sparkling wines at 120ml, fortified wines 60ml and spirits 30ml.
"I think it should be at each venue's discretion as to how they best like to serve their wine, including how much but ... I think every venue should be listing what is a standard glass of wine in that venue and to adhere to that. I think it's important to give people what they expect."
Ms Humble is pedantic about delivering exactly what her patrons expect. She uses a wine dispenser that dispenses wine directly from the bottle to exactly 100ml or 150ml. They also use badged glasses.
She says an alternative to the costly task of putting plimsoll lines on every glass would be to decant wine into a measured vessel before serving rather than pouring straight from the bottle.
She adds that the responsibility of pouring accurately is not just to the consumer, but to the employer, as over-pouring can be expensive.
Circa recently increased its wine servings from 100ml to 150ml because "we've often found that 100ml does have the perception of not being enough".
So what is the perfect amount of wine to put in a glass?
Ms Humble says: "I'm quite happy with 100ml as a standard pour because 100ml is one standard drink, so that way people can obviously monitor what they're having if they are driving or for health reasons ... For me I wouldn't like any more than 150ml in my glass simply because I like to swirl, to enjoy, to understand what I'm drinking."
WHAT WE FOUND
Cookie, Swanston Street, City - Dragonfly Willow Bridge Shiraz, $9 - 190ml (plain glass - no plimsoll line or badge)
Cafe L'incontro, Swanston Street, Lindeman's Shiraz Bin 50, $7 - 150ml (plimsoll line)
Transport, Federation Square – The Story Tinkers Shiraz, $10 - 160ml (plimsoll line)
The Carlton, Bourke Street, City – Paringa Shiraz, $8 - 160ml (badged glass)
The Bridge Hotel, Richmond – Scotts Shiraz, $8.50 - 150ml (plimsoll line)
Bridie O'Reilly's, South Yarra – Little Berry Shiraz, $8.50 - 150ml (plimsoll line)
The Railway Hotel, Windsor – Railway Shiraz, $7 - 150ml (badged glass)
Patee Thai, Prahran – McWilliams Shiraz, $7 - 145ml (plain glass - no plimsoll line or badge)
Saigon Rose, Chapel Street – Grant Burge "The Vigneron" Shiraz, $9 - 170ml (badged glass)
Spoonbill, at the Olsen Hotel, South Yarra – 2011 Dandelion Lionheart Shiraz, $11 - 155ml (badged glass)