Choose by the caffeine in the whole can, then compare sugar and can size. Red Bull states that its 250ml Original can contains 80mg caffeine and 27g sugar, while Monster Energy UK states that its 500ml Ultra can contains 150mg caffeine and 0g sugar: zero sugar does not mean less caffeine per can. Count other caffeine sources during the day, and check the intended drink’s warnings before buying it for someone who is younger, pregnant or sensitive to caffeine.
For a long moving-in day, compare caffeine in the complete can rather than treating a 250ml and a 500ml drink as equivalent. Red Bull states 80mg per 250ml Original can; Monster Energy UK states 150mg per 500ml Ultra can and 160mg per 500ml Original Green can.
Check sugar and caffeine separately. Monster Energy UK states that its 500ml Ultra can has 0g sugar but still contains 150mg caffeine.
Check the recipient’s circumstances and the exact product warning before choosing a flavour. Relentless says its White Citrus drink is not recommended for children, people sensitive to caffeine or those who are pregnant or nursing.
Start with the amount you would consume from the full can, then compare sugar declarations and any warnings that apply to the person drinking it.
| Priority | What to check | Your needs |
|---|---|---|
| Caffeine per can | Read the caffeine amount for the full can. If the label gives mg per 100ml, use the can volume to calculate the complete serving; also count caffeine from other drinks and foods. | I would rather compare the amount I might drink at once than judge a 250ml and a 500ml can by size alone. |
| Sugar formulation | Compare sugars for the named variant and complete can. Check caffeine separately: a zero-sugar declaration does not give the caffeine amount. | If I want zero sugar, I still need to decide whether the caffeine in that particular can suits the occasion. |
| Warnings and age | Read the product’s high-caffeine warning and check who the drink is intended for. For pregnancy, the NHS says to count caffeine from all sources within its 200mg daily limit. | When buying for someone else, I want to check their age and any relevant caffeine warning before choosing a brand or flavour. |
Red Bull states that Original contains 80mg caffeine per 250ml can, while Monster Energy UK states 150mg for Ultra and 160mg for Original Green in their respective 500ml cans.
Compare the caffeine in the full container. For a per-100ml figure, multiply it by the number of 100ml portions in the can.
Monster Ultra has 0g sugar and 150mg caffeine per 500ml can, according to Monster Energy UK. Tesco labels its 500ml Blue Spark Sugar Free at 30mg caffeine per 100ml, also 150mg per can.
Make separate checks for sugars and caffeine on the exact variant you plan to drink.
Red Bull states 27g sugars in a 250ml Original can; Monster Energy UK states 55g in a 500ml Original Green can. Those figures apply to the named regular variants, not every drink from either brand.
Read sugars for the whole can and check whether the label says regular, sugar free or no added sugars.
Product warnings can exclude particular groups. Separately, the UK government announced plans for an England-only ban on sales to under-16s of drinks containing more than 150mg caffeine per litre, excluding tea and coffee, from April 2027; that is not a current UK-wide rule.
Check the drink’s warning, the buyer’s age and the rules applicable where it is sold rather than relying on a general assumption about students.
These examples show why the exact variant and can size matter more than the brand name alone.
Red Bull states that its Original energy drink contains 80mg caffeine per 250ml can.
Monster Energy UK gives complete-can figures for both Ultra and Original Green in 500ml cans.
Relentless describes White Citrus as a carbonated citrus-flavour energy drink.
Lucozade describes Alert as a sparkling, high-caffeine drink range.
Tesco describes Blue Spark Energy Drink Sugar Free as a carbonated, sugar-free 500ml drink.
These sparkling drinks include smaller 250ml cans and a zero-sugar 500ml variant. Compare each pack’s exact formulation and caffeine per can rather than applying one variant’s figures to another.
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A smaller-can choice for someone comparing caffeine per complete serving while avoiding sugar. The listing states 80mg caffeine per 250ml can and 0g sugars per 100ml; it also identifies a source of phenylalanine. Check the ingredients and product warnings if they are relevant to the person drinking it.
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A regular sugar-containing option in smaller cans. The listing states 80mg caffeine per 250ml can, while Red Bull states 27g sugars per 250ml Original can. Count caffeine from other sources as well, and read the product warning before buying for someone else.
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A zero-sugar sparkling option for someone who wants a 500ml can. The listing states 0g sugars per can and 30mg caffeine per 100ml, equivalent to 150mg in the full can. It recommends no more than one can per day; check its label and count other caffeine sources too.
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A lightly sparkling cherry-flavour matcha drink in smaller cans. The listing states 80mg caffeine per 250ml can and says there are no added sugars, while declaring 3.7g sugars per 100ml. No added sugars is not the same as sugar free; check the packaging for ingredients and warnings relevant to the person drinking it.
Count caffeine from energy drinks alongside coffee, tea and caffeine-containing supplements. Food Standards Scotland and the Food Standards Agency state that intakes of up to 400mg per day are unlikely to cause adverse effects in adults; that is guidance about total intake, not a target to reach.
Check the drink’s warning and caffeine amount, then count caffeine from all foods and drinks. The NHS says pregnant people should not have more than 200mg caffeine a day, including caffeine from energy drinks, coffee, tea and other sources. Seek individual clinical advice if needed.
There is no UK-wide rule established by the announced England measure. The UK government announced plans to ban sales in England to under-16s of drinks containing more than 150mg caffeine per litre, excluding tea and coffee, from April 2027. Check the applicable rules and retailer conditions at the time of purchase rather than treating the planned England measure as already in force everywhere.
No. Monster Energy UK states that its 500ml Ultra can contains 0g sugar and 150mg caffeine. Tesco labels its 500ml Blue Spark Sugar Free at 30mg caffeine per 100ml, also 150mg per full can. Compare the sugar declaration and complete-can caffeine amount separately for the exact variant you choose.