Coffee shops: 'Huge' difference in caffeine between Costa, Starbucks, Greggs and Pret a Manger

High-street coffee chains offer “huge” differences in the amount of caffeine they serve, leaving customers with little idea how much they are consuming, a study has found.

A medium cappuccino at Costa contains a “massive” 325mg of caffeine – around the amount contained in four cups of tea – almost five times the strength of a cappuccino from Starbucks, which contains the least at 66mg, Which? found.

Cappuccinos from Greggs and Pret a Manger also contain significantly less caffeine than Costa, as 197mg and 180mg respectively.

By comparison, a 250ml can of Red Bull contains 80mg of caffeine.

A single espresso from Pret a Manger contains 180mg of caffeine, six times as much as one from Starbucks which had a “meagre” 33mg by comparison, according to the watchdog’s findings.

Pret a Manger’s filter coffee also contained the most caffeine at 271mg, 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.

Caffè 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, and there are also variations in taste between the two.

However, the findings show 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.

Which? nutritionist Shefalee Loth said: “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.

“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.”