When you order an espresso at a specialty cafe, it is likely they will serve you a double shot. How much caffeine is in that double shot of espresso? A double shot of espresso, which is around 2oz, will contain about 150mg of caffeine – add 75mg for each additional shot.
Eight ounces (or 237ml) of green tea can contain up to 28mg of caffeine. The same amount of black tea contains up to 47mg according to the Mayo Clinic .
Why is there such a big difference in the amount of caffeine reported in coffee and tea?
Coffee and tea are made from a natural product, and there can be variance in the amount of caffeine between different coffees and teas. Most brewed coffee from cafes nowadays are made from Arabica beans. However, a lot of instant coffees are made from Robusta beans which contain almost twice as much caffeine! Strength of the brew recipe varies between every cafe – ie. the ratio of coffee grounds to the amount of water used for brewing. Similarly for tea, the brew time and method can affect the amount of caffeine that is extracted.