Alcohol units: What are they and how are they measured?
Alcohol-specific deaths are alarmingly on the rise and have, according to research by the Office of National Statistics, increased by 33 per cent since 2019 to reach a record high.
Staying on top of our drinking has clearly never been more important. But calculating exactly how much alcohol we are consuming is easier said than done, especially with an ever-increasing and varied range of drinks on offer.
The “unit” of alcohol was introduced in an attempt to make things more straightforward but working out exactly many units are in a glass of champagne (1.5) or a glass of red wine (3.3) can be surprising and confusing. Read on to find out how to keep track.
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Understanding alcohol by volume (ABV)
Alcohol by volume or ABV determines the strength of a drink. ABV is a measure of the amount of pure alcohol (ethanol) as a percentage of the overall volume of liquid in a drink. The higher the percentage, the stronger the alcohol. So, for example, pure alcohol has a strength of 100 per cent ABV while water has 0 per cent ABV.
The ABV of each drink differs, but a common ABV level is between 5-12 per cent. Beer commonly has 5-6 per cent ABV, while wine ABVs range from 12-16 per cent and spirits such as gin, vodka and tequila average between 35-50 per cent ABV. At the other end of the scale, there are low-alcohol drinks, classified as anything with an ABV of below 1.2 per cent.
You can find the ABV on the labels of cans and bottles. It may be marked ABV or Vol (for volume). ABV is important because to work out the number of units in a drink you will need to know the percentage ABV of the alcohol and use that number in the equation outlined below.
What is an alcohol unit?
The “unit” of alcohol was brought in in 1987 as a standardised measurement to help us keep better track of our drinking. Following a report by the Royal College of Physicians, the government suggested guidelines for “sensible drinking” to be defined through units rather than through drinks.
Units provide a simple way to calculate the quantity of pure alcohol in a drink using its strength and size, while understanding how many units are in our drinks can help us think more carefully about how much we drink and plan the way we spread out our drinking.
One unit is equal to 10ml or 8g of pure alcohol (ethanol), which is about the amount a healthy adult liver can process in an hour.
Calculating alcohol units
Once we know the strength of your drink (per cent ABV) and the amount of the drink you’re having (volume in millilitres), you can work out how many units of alcohol are in your drink by using the following equation:
Strength (ABV per cent) x the volume of the drink (in millilitres) ÷ 1,000 = the total number of units in your drink
So, to find the number of units in a pint of 4 per cent ABV beer, calculate:
4 x 568 (ml) ÷ 1,000 = 2.3 units
or
For a medium-sized glass of 13 per cent ABV wine calculate:
13 x 175 (ml) ÷ 1,000 = 2.3 units
By far the quickest and most reliable way to work out how many units of alcohol are in your drink however is with a unit calculator.
Joe Marley, the director of communications for Alcohol Change UK, says: ‘Not everyone finds calculating the number of units in a drink easy – if you’re pouring a drink at home you might not be sure about the size of your measure, the strength of drinks can vary massively and, let’s face it, you might not feel that confident about your mental maths skills. We also have a quiz so you can check how healthy your drinking habits are. And our free Try Dry app lets you track your drinking and set personalised goals for cutting down.”
If you’re not tech-savvy why not print out a list of units and keep it in your wallet.
Drinking guidelines
In the UK, the government guidelines around alcohol consumption are issued by the chief medical officer. They state that to keep health risks from alcohol to a low level, men and women are advised to consume no more than 14 units per week and that this should be spread evenly over at least three days.
This equates to six pints of average-strength beer, 10 small glasses of lower-strength wine or 14 single measures of spirit.
Guidelines are around “low risk” drinking, as consumption of alcohol can have an impact on health and there is no “safe” drinking level.
Illnesses which can develop after a decade or more of regularly exceeding 14 weekly units include:
Liver disease
Heart disease
Risk of stroke
Developing certain cancers
Damage to the brain and or nervous system
Regular drinking can also negatively impact our mental health
Reacting to new data released last month by the Office of National Statistics, Dr Katherine Severi, the chief executive of the Institute of Alcohol Studies, called for more action from the UK Government to reduce alcohol harm. “Alcohol is the biggest killer of working-age people,” she said. “Year after year we’ve seen tragic increases in deaths from alcohol, which disproportionately affect the most deprived communities. The rise has also been especially high among women, with 37 per cent more deaths than in 2019.”
Frequently asked questions
Why do we bother with units, why can’t we just use glasses?
The strength of alcohol is different. So, you could have two identical-sized glasses, one full of wine, the other full of beer and you would have consumed the same volume of liquid but not the same amount of alcohol, as the alcoholic content of wine is stronger than that of beer. The “unit” makes it possible to make comparisons and add together drinks of different sizes and strength, to keep track of overall consumption.
Can I use the same system of units while abroad?
With no guidelines from the World Health Organization, countries across the globe set their own, which differ wildly; some advise a weekly unit, some per day, while some differentiate between men and women. For example:
Belgium recommends 17 units a week for women and 26 for men.
Italy’s recommendations are one unit a day for women and two for men.
To further confuse matters, the unit measurement itself can change. While in the United States, one unit contains 14g alcohol, in Australia it is 10g while in the UK just 8g.
If I can look up units via a unit calculator why do I need to know about ABV?
Besides denoting strength of a drink, ABV indicates how it will taste. Home mixologists should remember that drinks with a higher ABV are harsher on the tongue because of the stronger alcohol content.
Is ABV the same as proof?
Proof is a term dating to medieval England when spirits were burnt to test strength. ABV has replaced the use of “proof” in the UK since 1980. The term is still used in the US but is defined as twice the percentage of ABV.
I think I’m drinking too much, what should I do?
If you’re worried about your drinking or want to find out more, visit the Alcohol Change UK website. You can also find independent information and advice on the websites of drinkaware.co.uk and drinkcoach.org.uk.
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