Units and calories in hard seltzer
Get the facts on the unit and calorie content of hard seltzer
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Hard seltzers are a type of pre-mixed alcoholic drink made from carbonated water, with added alcohol and flavourings. Most commonly they have fruit-based flavours.
They are part of a broader category of alcoholic drinks sometimes called ‘ready to drink’, which includes pre-mixed cocktails (like a canned gin and tonic) and ‘alcopops’.
Hard seltzers aren’t just carbonated water - they contain alcohol. They aren’t suitable for anyone that needs to avoid alcohol, and they are illegal to buy for anyone under the age of 18.
To keep health risks from alcohol low, if you choose to drink hard seltzer, it’s important to stick to the UK Chief Medical Officers' low risk drinking guidelines. That means no more than 14 units a week, spread over three or more days, with several drink-free days - and no bingeing.
Regularly drinking more than the low risk drinking guidelines increases your risk of serious health conditions including heart problems, high blood pressure, poor mental health, alcohol-related liver disease and seven types of cancer.
Checking a hard seltzer's ABV (alcohol by volume) tells you what percentage of the drink is made up of alcohol. For example, a hard seltzer with 5% ABV is five percent pure alcohol – and the higher the percentage, the more alcohol there is.
On average, drinks that are part of the ‘ready to drink’ category, including hard seltzers, are 4.6% ABV. But that’s only an average. The only way to be sure of the strength of a particular hard seltzer is to check the label, or ask at the bar.
A good way to keep track of how much you’re drinking is to know how many units of alcohol are in your drink. One unit of alcohol is 10ml (ten millilitres) of pure alcohol – the number of units you are drinking depends on the drink’s size and strength.
A 330ml can of average strength (4.6% ABV) hard seltzer has about 1.5 units in it.
Alcohol contains around seven calories a gram - almost as many as pure fat, so even if the hard seltzer doesn’t have any added sugar, it might have more calories in it than you expect.
Some hard seltzers display calorie information on the label. But if you’re counting calories, choosing a low alcohol drink (up to 1.2% ABV) means the drink is legally required to show this information.2,3
Drinking alcohol also interferes with the way fat is metabolised in your body.4 Research has also found that the calories people consume through alcohol are usually additional to the calories in the rest of their diet, rather than a replacement.5
Hard seltzers taste very similar to soft drinks, but of course they are not. In addition to the longer-term health effects of alcohol, like any other alcoholic drink, the alcohol in a hard seltzer dehydrates you and your skin every time you drink.6 Try drinking sparkling water, or a diet soft drink instead of a hard seltzer - switching will help you stay hydrated, and slow down the rate you’re drinking.
Drinking in rounds means that you’re keeping up with the fastest drinker, so you could be consuming your units faster than you’d like. Regain control, and maybe even save some cash, by buying your own drinks instead.
If you drink regularly, your body starts to build up a tolerance to alcohol. This is one of the reasons the UK Chief Medical Officers’ low risk drinking guidelines recommend having several drink free days each week, as well as not drinking more than 14 units per week.
If you choose to drink, recording exactly what you’ve drunk during the week will tell you whether you're keeping within the low-risk guidelines.
The free MyDrinkaware app is perfect for tracking your drinks at home and when you’re out and about.
 Department of Health and Social Care. Health and Care Bill: food information for consumers – powers to amend retained EU law. Available at: https://www.gov.uk/government/publications/health-and-care-bill-factsheets/health-and-care-bill-food-information-for-consumers-powers-to-amend-retained-eu-law [Accessed 7 December 2022]
 Regulation (EU) No 1169/2011 of the European Parliament and of the Council. Chapter IV. Section 3, Nutrition Declaration. Available at: https://www.legislation.gov.uk/eur/2011/1169/chapter/IV/section/3# [Accessed 7 December 2022].
 Sonko, B. J., Prentice, A. M., Murgatroyd, P. R., et al. (1994). Effect of alcohol on postmeal fat storage. Am J Clin Nutr, 59, 619-25.
 Kwok, A., Dordevic, A.L., Paton, G., Page, M.J. and Truby, H. (2019). Effect of alcohol consumption on food energy intake: a systematic review and meta-analysis. British Journal of Nutrition, 121(5), 481-495.
Last Reviewed: 7th March 2023
Next Review due: 7th March 2026