A double shot of espresso typically contains about 126 milligrams of caffeine. This amount can vary depending on factors such as the type of coffee bean, roast level, grind size, and extraction method, but 126 mg is a common average for a 2-ounce (60 ml) double shot (also called a doppio)

. To summarize:

• Single shot (1 oz): ~63 mg caffeine
• Double shot (2 oz): ~126 mg caffeine (often cited as the standard average)

Some sources give a wider range for a double shot, from about 58 mg up to 185 mg, but the typical figure is around 125-130 mg

. Thus, if you order a double shot of espresso, you can expect roughly 125-130 mg of caffeine on average.