For many of us coffee offers a much-needed boost, but we may be getting much more - or less - caffeine than we bargained for at popular High Street coffee shops. Consumer group Which? measured the caffeine in drinks at five big chains and says it found "huge differences".
An espresso at Pret for example had six times as much as one in Starbucks's. A medium cappuccino at Costa Coffee has 325mg of caffeine - far more than rival drinks and equal to four cups of tea.
Which? said consumers should be alert to caffeine levels. "Our research shows you may be consuming significantly more, or less, caffeine than you bargained for," said its nutritionist Shefalee Loth. "Most of the time this shouldn't be an issue but if you drink a lot of coffee or need to limit your caffeine intake you might want to consider what you're ordering and where from."
One coffee lover said: "I like my coffee - in fact, I travel that extra bit just go to Costa because I like the way they make their lattes.
"I was a bit surprised by this survey - by the extent of the variation of caffeine content. I had coffee once from McDonalds that gave me this huge caffeine kick…and then I crashed. I had to take a nap afterwards." Caffeine is a natural stimulant that can make you more alert. However, some people are sensitive to it or need to avoid it for health reasons, such as being pregnant.
Which? measured the caffeine levels in cappuccino, espresso and filter coffee at Caffè Nero, Costa, Greggs, Pret a Manger and Starbucks, and found:
- A Starbucks cappuccino contained the least caffeine at 66mg - less than the 75mg in a single tea bag - while Caffè Nero's had the second lowest levels (110-115mg)
- Greggs and Pret a Manger had the second and third-strongest cappuccino at 197mg and 180mg respectively
- Pret's single espresso was strongest at 180mg
- Starbucks' espresso was bottom of the table at just 33mg
- Pret topped the list for the most caffeinated filter coffee at 271mg a cup
- Greggs was a close second at 225mg
- Starbucks was again the least caffeinated at 102mg
One factor that can impact caffeine content of drinks is the type of coffee bean. Of the two main types used, Arabica beans contain around half the caffeine of Robusta beans, and there are also variations in taste between the two. Costa Coffee said the amount of caffeine in its drinks varied depending on size of a drink and the type of coffee used.
"We would encourage customers to be aware of the caffeine content in their favourite Costa coffee to ensure it is right for their dietary requirements or lifestyle choice," a spokeswoman said. Pret declined to comment, while the BBC has contacted Caffè Nero, Greggs and Starbucks for comment.