The caffeine concentration in the strongest espresso was three times higher than in the weakest in a test conducted at known locations.

A recent coffee test commissioned by the Hungarian Energy Drink Association revealed significant variations in caffeine content among espresso servings from different locations. The study involved purchasing espressos from 17 different venues, including specialty coffee shops and fast-food outlets, and measuring their caffeine levels using HPLC methods. Results showed that espresso sizes ranged from 18 to 45 milliliters, leading to discrepancies in caffeine concentration. The strongest espresso contained nearly three times the caffeine of the weakest. Overall, while the average caffeine content varied, the differences were less pronounced when excluding the smallest serving sizes.