The caffeine content of coffee can vary considerably depending on several factors, including the type, the brewing method, and the brand.

Here’s a small chart showing caffeine content that will give you an idea of how much caffeine there may be in your drink. 

• Espresso -  about 30–50 ml (1–1.75 oz), 63mg (0.002 oz) on average
• Brewed coffee (240ml or 8oz) - 70–140mg (0.0024–0.0049 oz) of caffeine, 95mg (0.003 oz) on average

Lattes, cappuccinos, macchiatos and Americanos 

• Small -  63mg of caffeine on average
• Double (large) - about 125mg
• Instant coffee - about 30–90 mg 
• Decaf coffee 0–7mg, 3mg on average 

If you’re a coffee drinker, you probably know that the two most popular species of plant for producing coffee beans are Coffea arabica (known as Arabica) and Coffea canephora (known as Robusta). 

A 2016 study found that Robusta coffee beans typically contain around twice as much caffeine as Arabica beans. 

Caffeine per kg of dry coffee:

Arabica - 34.1–38.5 g  

Robusta - 68.6–81.6 g 

Statistics

Dietary Guidelines for Americans 2015–2020: over 95% of adults in the U.S. consume foods and drinks containing caffeine. On average, they get between 110 and 260 mg of caffeine every day.