Awareness of unit content of self poured drinks by UK adults: a useful intervention tool

21 February 2008


Jan Gill and Fiona O’May, Queen Margaret University, Edinburgh. A full report of the study has been accepted for publication in Alcohol and Alcoholism.

Key findings

Of participants (n=304) seven were non drinkers (2.3% of the sample) and the findings described below relate only to the drinkers.

  • Drinking at home ‘often’ or ‘occasionally’ was reported by 97.5% of men and 93.6% of women. In this location the volume of wine or spirit poured is likely to be controlled by the drinker (not a barperson or waiter).
  • The average drink poured by this sample contained not 1.0 but 2.05 UK units (95% CI = 1.970-2.125; SD = 0.678, n= 297).
  • Only a quarter of all participants were able to estimate the unit content of their poured drink with some degree of accuracy. Just under a tenth offered no guess while the remaining participants were almost equally split between two groups who either ‘under’ or ‘over’ estimated their drink unit content. It is interesting that the more concerning group from a health risk perspective, the ‘under estimators’, also poured significantly more alcohol than the other groups.
  • The group who guessed the unit content of their poured drink with some degree of accuracy (within 10%), nevertheless poured a mean drink of 1.95 UK units. This finding suggests that for some in the population the double measure is not poured in ignorance.
  • The size of glass appears to correlate positively with the volume of wine poured. The difference between the mean volume of wine poured into the largest wine glass compared to the smallest was one third of a UK unit. The wine glasses employed in the study were selected because (a) they could be purchased from four well known UK retailers and (b) they were all marketed as ‘small glasses’.
  • Just under half (49.2%) of all participants did not know daily guidelines for their gender or provided an inaccurate answer. Almost 80% of all participants claimed not to use the UK ‘Sensible Drinking Guidelines’ to direct drinking. There were no differences between the genders in this respect.
  • When each participant was made aware of their limits for the daily consumption of alcohol in terms of their personally poured drink, 46% ( n= 132) of respondents stated that they would drink more than this on a single day or at the weekend while 32.4% (n=93) felt they drank within this limit.
  • Only 20.5% of the sample suggested that the pouring test result might influence their future pouring of drinks. Around 70% (70.5%, n=43) of this group were female.

Note: This report was funded and/or written by our predecessor organisation, the Alcohol Education Research Council (AERC).


Inappropriate alcohol consumption in the UK is linked with considerable human and financial cost and the case for effective measures to address this issue is well argued. An important component of current UK alcohol policy is the ‘Sensible Drinking’ message introduced in 1995 by the Department of Health which promotes limiting daily intake of alcohol to 2 – 3 UK units for women and 3 – 4 UK units for men.

The effectiveness of this message is partly dependent on a clear understanding among drinkers of the term ‘unit’ used to quantify alcohol drinks. Early guidance equated a unit of alcohol with a ‘measure’ of spirit or a ‘glass’ of wine. However there is evidence to suggest that among the general public some confusion exists around the content of the message and the concept of a unit of alcohol. It may be that a section of the UK population unwittingly exceeds recommended daily consumption guidelines purely for these reasons.

In this report we describe the piloting of a simple practical intervention tool. Each participant in this study was asked to pour the drink of wine or spirit they would pour at home into a glass they selected from six (four wine, two spirit) purchased from UK ‘high street’ stores. The unit content of their poured drink and their personal daily limit in terms of this drink were then calculated and relayed back to the participant and their reaction noted. We hoped this exercise might illustrate in a very personal way the volume of alcoholic drink associated with their daily limits of consumption and thereby re-enforce the detail of campaigns promoting responsible drinking.

Data were collected during a ten day period in December 2006. Study participants were either employees of a major UK financial institution or, staff and students located at an academic institution in the same city. In addition to the pouring test, each participant completed a short questionnaire relating to the UK Sensible Drinking message.


  • The finding that self-poured drinks of wine and spirit contain, on average, two units of alcohol not one, is not new. We have demonstrated this fact before, but two interesting points emerge. Firstly we have now shown that it is also true when people pour drinks into glasses of a style more likely to be found in the home and secondly, reasonable awareness of the unit content of a self-poured drink was demonstrated by only around a quarter of participants.
  • Population surveys which monitor consumption must recognise the generosity of self-poured drinks. Only eight participants (2.7% of drinkers) poured one or fewer units.)
  • Recent health literature has begun to recognise the previous point and to stress that glasses of wine cannot be equated to single units of alcohol.Perhaps more needs to be said in relation to self-poured drinks of spirit.
  • Amongst this convenience sample recruited from office workers academics and students there is evidence of poor recall and perceived relevance of the current UK Sensible Drinking message.
  • A large percentage of the sample do not use the present health message in the UK to guide their drinking. A re-drafting may be timely. On the basis of the alcohol content of the drinks poured in this study, it may be appropriate for women to consider a rewording of the sensible drinking guidelines to ‘one drink per day’. In this study, 20% (n= 28) of women poured 2.5 or more units in a single drink. (The daily limits for women are 2-3 units).
  • This study’s findings including participants’ suggested initiatives which might help people to drink within a healthy limit, have implications for both manufacturers of drink ( 35.6% of respondents favoured measures designed to aid the consumer quantify their consumption like drink labelling, bottle marking etc), and, secondly, of glassware – there is preliminary evidence from this study to suggest that increasing glass size is associated with increased volume of poured drink. (It is worth stressing that all wine glasses used in this study were marketed as ‘small’).
  • Also of relevance is the fact that a relatively common response to the discussion of personal daily limits of consumption was that this limit would not be exceeded through the week, but that units could be saved for the weekend. Any re-wording of health guidelines needs to address this confusion more emphatically.
  • The use in this study of a practical illustration of ‘Sensible Drinking’ limits in terms of personal drink volumes appeared to ‘reach’ relatively few of the participants, around 20% claiming that it would influence future pouring (with woman possibly being more receptive to its delivery). We do not know the ‘honesty’ of this reply. Some may have been reluctant to admit ignorance around their own level of consumption. Others may have responded positively to ‘please’ the interviewer. Additionally we cannot assume that the future pouring of drinks will be ‘positively’ influenced.
  • Further work to investigate a larger and more representative sample is merited.