Units and calories in rum
Get the low-down on how many units and calories are in rum and rum-based drinks.
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Rum is a spirit made from sugar cane juice or fermented molasses that comes in both white and dark varieties. It’s commonly used in cocktails and mixed drinks.
Like all spirits, rum has a high alcohol content. Legally, any rum sold in the UK must be at least 37.5% alcohol by volume (ABV).1 That means 37.5 percent of the drink is pure alcohol - and if the ABV is higher, the percentage of alcohol is higher too.
To keep health risks from alcohol low, if you choose to drink, 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.
Drinking alcohol also causes at least seven types of cancer, including breast, bowel, mouth and throat cancers.2 The risk of developing these types of cancer starts to increase even at low levels of drinking - so the less you drink, the more you reduce your risk.
Checking the ABV (alcohol by volume) of rum will tell you what percentage of the drink is made up of alcohol. The higher the percentage, the more alcohol there is - for example, half of a 50% ABV rum is pure alcohol.
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 – and the number of units you are drinking depends on the drink’s size and strength.
Pubs and bars used to commonly serve spirits like rum in 25ml measures. But these days many pubs and bars have switched to 35ml or 50ml measures – meaning you might be having a lot more alcohol without realising.
And if you drink rum as part of a mixed drink or a cocktail, it’s worth remembering there can be several measures – even if the drink doesn’t taste particularly strong. If you drink at home, a good way to avoid accidentally pouring too much rum and limit how your alcohol intake is to use a unit measuring cup.
Alcohol contains around seven calories a gram, almost as many as pure fat. This means that because rum contain lots of alcohol, it’s high in calories too.
A single (25ml) measure of 40% ABV rum can contain around 60 calories
And don’t forget that in a cocktail the mixer also adds to the overall calorie count. Just like in other alcoholic drinks, these are ‘empty calories’ with no nutritional value, so don’t benefit your body in any way.
Drinking rum, or other alcoholic drinks, means you will be taking on extra calories on top of your food.3 And because alcohol also reduces the amount of fat your body burns for energy,4 drinking can lead to weight gain.
Flavoured colas and authentic ginger beer served with lime and plenty of crushed ice are the key to creating sophisticated alcohol-free Dark and Stormy-type drinks. Choose sugar-free options to cut out extra calories.
Planning in a few alcohol-free days is a simple way to help stay within the unit guidelines. Put them into your phone’s calendar, so you won’t forget.
Drinking in rounds means you’re sipping at the speed of the fastest-drinking person in your group. Opt out and go at your own pace instead.
 Gapstur et al., 2021, Alcohol and Cancer: Existing Knowledge and Evidence Gaps Across the Cancer Continuum. Cancer Epidemiol Biomarkers Prev. 2021 Nov 2; cebp.0934.2021. doi: 10.1158/1055-9965.EPI-21-0934
 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.
 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.
Last Reviewed: 16th February 2023
Next Review due: 16th February 2026