The science of alcohol
The science of alcohol

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

Free course

The science of alcohol

1.1 Units of alcohol

A unit of alcohol is a measure of the volume of pure alcohol contained in an alcoholic drink. In the UK, one unit of alcohol is equivalent to 10 ml of pure alcohol, regardless of what type of drink is involved. Table 1 gives some examples of drinks and the approximate number of UK units of alcohol they contain.

Table 1 Number of units of alcohol in common alcoholic drinks in the UK, where 1 unit equals 10 ml of pure alcohol.

A pint of ordinary strength lager (4% ABV) 2 units
A pint of strong lager (5.5% ABV) 3 units
A pint of ordinary bitter (4% ABV) 2 units
A pint of best bitter (5.2% ABV) 3 units
A pint of ordinary strength cider (5% ABV) 2 units
A pint of strong cider (5.2% ABV) 3 units
A 175 ml glass of red or white wine (12% ABV) ~ 2 units
A pub measure (optic) of spirits (25 ml) 1 unit
An alcopop ~ 1.5 units

In the early 1990s, the UK Government recommended that men should not drink more than 21 units per week while women should not drink more than 14 units per week.

However, after the initial guidance was provided, it quickly became apparent that many people were not distributing this consumption equally throughout the week and, as you have seen, this can be harmful. Therefore, more recent (2014) advice [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] recommends a maximum number of units of alcohol per day. For men, this is 3–4 units of their weekly maximum of 21 units and, for women, this is 2–3 units of their maximum of 14 units per week.

In 2016, new guidance was issued by the Department of Health. The Chief Medical Officers' guideline for both men and women states that:

To keep health risks from alcohol to a low level it is safest not to drink more than 14 units a week on a regular basis

If you regularly drink as much as 14 units per week, it's best to spread your drinking evenly over three or more days. If you have one or two heavy drinking episodes a week, you increase your risk of long-term illness and injury.

Even with this guidance, it still remains a challenge for individuals to calculate the number of units they are drinking, even if they consider it a valuable exercise to keep track.

The Portman Group has a code of practice stating that a product must have the following labelling on it to promote responsibility:

  • unit alcohol content per container (and optionally per typical serving)
  • pregnancy logo and message – to alert drinkers to the dangers of drinking while pregnant
  • active signposting to the Drinkaware website.

The labelling used by the Cotswold Distillery on the reverse of their gin bottles is illustrated in Figure 3.

Described image
Figure 3 Product labelling to promote responsible drinking

Activity 2 Consumption awareness

Timing: Allow about 10 minutes

Watch the following video in which two different groups of students at an English university discuss their alcohol consumption including their understanding of UK units.

Download this video clip.Video player: sdk100_2015j_vid014-640x360.mp4
Skip transcript

Transcript

SUBJECT 1

We usually start with wine and maybe progress to, like, some sort of shots of some sort. But or no-- you mean--

INTERVIEWER 1

So what--

SUBJECT 1

--unit-wise, or--

INTERVIEWER 1

--what might you, what you might-- No, just tell me.

SUBJECT 1

We might have, um--

SUBJECT 2

A bottle of wine each.

SUBJECT 1

Hm, well.

SUBJECT 2

Yeah.

SUBJECT 1

Yeah, often, maybe a bottle of wine each.

SUBJECT 2

Yeah.

SUBJECT 1

Or maybe three, four beers, followed by--

SUBJECT 2

--whatever spirits we have.

SUBJECT 1

Either vodka--

INTERVIEWER

Or some shots.

SUBJECT 1

Some shots.

[LAUGHS]

Yeah.

SUBJECT 3

It depends, because-- because you drink different things, as well, don't you? Like, I might start out-- personally, I always start with, like, a few pints. And then--

INTERVIEWER 2

A few pints?

SUBJECT 4

And then have--

INTERVIEWER 2

You start with a few pints.

SUBJECT 4

Well, if we're-- it's like a serious night, and then, and then have moved-- and then after a while, I get really full, so I don't want to drink beer anymore. So I'll have, like, mixers-- vodka and Coke or something instead, or vodka and Red Bull. And then I think, so yeah, you probably could work it out of an average night out in, like, units, or something. But I don't know.

INTERVIEWER 1

How many units do you think are in a pint?

SUBJECT 4

There's just 2 in a pint, isn't it? Just 2.

INTERVIEWER 1

Ordinary beer, yeah.

SUBJECT 4

Yeah.

INTERVIEWER 1

Yeah.

SUBJECT 4

So 2 in a pint.

INTERVIEWER 1

More, if it's the strong lager.

SUBJECT 4

Yeah, OK. So if it's like, like what? Like, if it's more than 5% or something.

INTERVIEWER 1

If it's more than 5%.

SUBJECT 4

Yeah, OK.

INTERVIEWER 2

Are you happy?

INTERVIEWER 1

How much are you--

SUBJECT 4

Well, I'm just trying to-- no, I'm just trying to think.

SUBJECT 5

I'm just starting to think, it's probably easier to answer what it's like if you go to someone's house to drink, because then you buy what you have. And it could probably be a bottle of wine, and then maybe something more.

INTERVIEWER 1

How much of the wine would you drink?

SUBJECT 5

Most of it.

INTERVIEWER 1

Of-- about a bottle. And how many units do you reckon are in a bottle?

SUBJECT 5

Uh, I have no idea [? of it. ?]

INTERVIEWER 1

Any ideas?

SUBJECT 4

In a bottle?

INTERVIEWER 1

In a bottle of wine.

SUBJECT 4

Um, is it something like 10 units?

INTERVIEWER 1

I think so.

SUBJECT 4

It's some more, isn't it? I don't-- I really have no clue.

INTERVIEWER 1

It's about, it's about 8, about 8 or 9.

SUBJECT 6

8 or 9, isn't it.

SUBJECT 5

Oh, yeah.

SUBJECT 4

But yeah, OK, so think about it. It's going to be something like probably 20 units, because if you have, say--

SUBJECT 6

--a big night out.

SUBJECT 4

--six pints, that's 12 units, and then three doubles or something, that's another 6 units. And so, yeah, I think it adds up quite quickly.

INTERVIEWER 2

Yes.

SUBJECT 4

And then if you have a really crazy night-- like, it's your birthday or something, who knows?

SUBJECT 6

Oh, yeah.

[LAUGHS]

Who knows what could happen.

SUBJECT 5

How much is a shot, like, a vodka shot--

INTERVIEWER 1

About 1 and 1/2, I think.

SUBJECT 5

OK.

INTERVIEWER 1

I mean, like 1 and 1/2, it may be, may be 2. And if you drink a bottle of wine, roughly how many units do you think are in a bottle of wine?

SUBJECT 1

About 3.

SUBJECT 3

Oh wait, I read it yesterday-- no, no. 5 6.

SUBJECT 1

Wait, no, 7.

SUBJECT 2

6, 7.

SUBJECT 1

Yeah.

INTERVIEWER 1

7, 3?

[LAUGHS]

SUBJECT 7

I have no idea what any of it is.

SUBJECT 8

I think a pint-- a pint is 2 units, isn't it? Yeah, a pint is 2 units.

INTERVIEWER 1

Of what? A pint of--

INTERVIEWER 2

Of beer.

SUBJECT 8

Beer, yeah.

INTERVIEWER 1

Ordinary beer, Stella?

SUBJECT 8

Yeah, no, not Stella. Carling, probably.

INTERVIEWER 1

Yeah.

SUBJECT 8

I mean, what are your average? 4.5%, isn't it?

INTERVIEWER 1

A bit less. The ordinary beers are about 3, I think.

SUBJECT 8

Yeah, something like that, yeah?

SUBJECT 3

What's Carling?

SUBJECT 8

4.1%.

INTERVIEWER 1

Oh, is it, yeah, OK.

End transcript
 
Interactive feature not available in single page view (see it in standard view).

What do you notice about their understanding? Note any thoughts you have in the box below before reading the discussion.

You can type text here, but this facility requires a free OU account. Sign in or register.
Interactive feature not available in single page view (see it in standard view).

Discussion

Both groups of students can recall what they drink but very few had an awareness of how many units this equated to, with one student commenting that she did not know what a unit was. Estimations for the number of units in a bottle of wine varied from three to ten units, whereas it is actually eight to ten units in the UK. Some students also described alcohol in terms of percentage volume, rather than units. In most cases, what students reported drinking in one evening exceeded the recommended amounts.

SOA_1

Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to university level study, find out more about the types of qualifications we offer, including our entry level Access courses and Certificates.

Not ready for University study then browse over 900 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus