A new study has revealed the "huge" differences in the amount of caffeine in coffees from leading high street chains like Costa, Starbucks and Pret A Manger.
Which? found that a medium cappuccino at Costa contains a "massive" 325mg of caffeine - around the amount contained in four cups of tea and almost five times stronger than a Starbucks cappuccino.
While the variations are not only due to the number of caffeine shots used across the chains, nutritionists say you may be consuming "significantly more or less caffeine than you bargained for".
The study found that cappuccinos from Greggs and Pret A Manger contain significantly less caffeine than Costa, at 197mg and 180mg respectively. By comparison, a 250ml can of Red Bull contains 80mg of caffeine.
When it comes to a single espresso, one from Starbucks contains a "meagre" 33mg of caffeine - meaning at 180mg, one from Pret contains almost six times more.
On filter coffee, Pret A Manger led the way with the most caffeine at 271mg - two-and-a-half times as much as the Starbucks version, which contained 102mg. Greggs was a close second containing 225mg.
The variations are also due to the type of coffee beans used, of which there are two main types - Arabica and Robusta.
Arabica beans contain around half the caffeine of Robusta beans, and there are also variations in taste between the two.
'Big variations in caffeine content'
Which? nutritionist Shefalee Loth said the research shows you may be consuming significantly more, or less, caffeine than you bargained for.
"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."
The findings also show that buying coffee on the high street could 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.
A Costa Coffee spokeswoman said:
"The amount of caffeine included within each coffee varies, depending on both the coffee and size of drink ordered by a customer."
Pret A Manger declined to comment.
(c) Sky News 2023: Revealed: Which chains put a 'massive' amount of caffeine in their coffees... and which don't
Five Alternative Christmas Dinners For Turkey Haters
Five Brilliant Food Games For All The Family On Christmas Day
Five Most Unique Christmas Dinners Worldwide
Five Best UK Christmas Attractions To Visit
Five Horror Christmas Films For Adults Only