A science-based guide to the caffeine in your coffee.

a science-based resource on coffee, caffeine, and health


Caffeine crystal viewed from an electron microscope. Credit: Annie Cavanagh and David McCarthy



Many of coffee's potential benefits are associated with caffeine, a naturally occurring stimulant found in the bean.

Caffeine occurs naturally in the leaves and seeds (or "beans") of the coffee tree. Scientists think caffeine, which has a bitter flavor, originally evolved to protect plants from predators.

Caffeine is strongly associated with coffee - even the legend about coffee’s origins is linked to its (much appreciated) energizing effects. As a result, coffee has gained popularity and recognition as a natural stimulant. Many consumers enjoy coffee each morning to start their day, and it's recommended as an afternoon pick-me-up. As a result, coffee drinkers are generally quite attuned to their individual caffeine tolerance and instinctively modulate their intake. However, some consumers find that decaf is a better option due to health concerns or physiological sensitivity. 

Many scientists have linked regular caffeinated coffee consumption to potential benefits that include improved athletic performance and cognitive function in older adults. Antioxidants and other compounds in coffee are linked with benefits that include helping to prevent liver disease, heart health, and lower diabetes risk

How Much Caffeine Is In Your Coffee?

A standard cup of brewed coffee (8 oz) contains an average 95 mg of caffeine, with a range of 75 – 165 mg. Even decaff coffee contains a small amount: an average of 2 mg per brewed 8 oz. [Source]

However, determining the exact amount of caffeine in any cup of coffee is complicated. Many factors can influence caffeine levels in coffee, including different varietals of coffee plants, different plants (even on the same farm), soil conditions, moisture variations - and especially brewing techniques.

For more information on caffeine content, visit the USDA National Nutrient Database for Standard Reference.

Caffeine and You

The stimulating properties of natural caffeine in coffee affect individuals differently. Coffee drinkers should also keep in mind that caffeine can also be found in other foods and beverages. 

Everything from heredity to body weight, gender, metabolism, age, and coffee drinking habits can affect how your body responds to the caffeine in coffee. In fact, genetically there are “fast caffeine metabolizers” versus slow ones. Slow metabolizers and others who are particularly sensitive to caffeine may avoid coffee before bedtime, for example, while others can drink coffee and sleep without issue. 

Regular drinkers tend to self-regulate their consumption instinctively. Some research findings link the caffeine in coffee to potential health benefits. Other naturally occurring compounds such as antioxidants are also frequently recognized as potentially favorable to health.