The coffee chains with the strongest caffeine kick... and the weakest
Grabbing a cup of coffee is a vital part of many commuters' mornings.
But now, a study of high street chains’ espresso, cappuccino and filter coffee has shown "huge" differences in the amount of caffeine served - leaving customers with little idea of just how much of a wake-up call they are getting.
Which?, the consumer watchdog, found that those hoping for a small pick-me-up could even be unwittingly consuming five times the amount of caffeine than the same drink from other stores.
According to the research, a medium cappuccino at Costa contained a "massive" 325mg of caffeine - around the amount contained in four cups of tea. This was five times the strength of a cappuccino from Starbucks, which contained the least at 66m, and three times that of Caffe Nero at 115mg.
Cappuccinos from Greggs and Pret A Manger also contained significantly less caffeine than Costa, at 197mg and 180mg respectively.
By comparison, a 250ml can of Red Bull contains 80mg of caffeine and a can of Coca-Cola contains 34mg.
When it came to espressos, a single shot at Pret A Manger contained 180mg of caffeine - six times as much as one from Starbucks, which had a "meagre" 33mg according to the consumer watchdog's findings.
Pret A Manger's filter coffee, which uses organic, Arabica beans, contained the most caffeine at 271mg. That is two and a half times as much as the Starbucks version, which contained 102mg.
Greggs was a close second to Pret for its caffeine levels, containing 225mg in a cup of filter coffee.
Caffe Nero had the second lowest levels of caffeine after Starbucks in both its cappuccinos, containing between 110mg and 115mg, and its espresso with 45mg.
The variations are not only due to the number of caffeine shots used across the chains but also the type of coffee bean, of which there are two main types - Arabica and Robusta.
Arabica beans contain around half the caffeine of Robusta beans. There are also variations in taste between the two.
For its analysis, Which? used cafe menus and verified the caffeine content with each coffee chain.
'Consider what you're ordering and where from'
The findings could be a boost for those seeking out a strong pick-me-up, but be potentially problematic for consumers who are sensitive to caffeine or are pregnant.
The NHS says pregnant women should consume no more than 200mg of caffeine per day, advising that a mug of instant coffee contains 100mg and a mug of filter coffee contains 140mg.
Caffeine acts as a stimulant, increasing activity in the brain and nervous system. It can temporarily make someone more alert or less drowsy, but can affect some people more than others.
Shefalee Loth, a nutritionist at Which?, said that customers who need to limit their caffeine intake should pay attention to where they shop.
"Many of us rely on coffee to get us through the dark winter mornings, but our research shows you may be consuming significantly more, or less, caffeine than you bargained for," she said.
"Our analysis has shown that there are big variations in caffeine content between drinks from different high street coffee shops.
"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."