How Much Caffeine Is in a Cup of Coffee?

A 12 oz cup of regular brewed coffee contains roughly 113 to 247 mg of caffeine, according to the FDA. That's a wide range, and real-world cups can fall outside it: lab tests of coffee-shop drinks have found the same coffee from the same store varying by more than double from one day to the next. Size, beans, and brewing all matter.

So the honest answer to how much caffeine in a cup of coffee is "it depends," but it's possible to estimate your own intake well enough to stay comfortable. Below are the numbers from lab studies and the FDA, what drives the differences, and how to keep track if you also care about caffeine before training or bed.

How Much Caffeine Is in Brewed Coffee?

Most regular brewed coffee lands somewhere between 113 and 247 mg per 12 oz, according to the FDA. Coffee-shop drinks can run higher because the cups are bigger. One lab study of specialty coffees found an average of 188 mg in a 16 oz cup, with individual drinks ranging from 58 to 259 mg.

The FDA's consumer guide on caffeine lists regular brewed, non-specialty coffee at 113 to 247 mg per 12 fluid ounces. It also notes that 400 mg a day, about two to three 12 oz cups, is an amount the FDA has cited for most healthy adults.

A 2003 study in the Journal of Analytical Toxicology measured caffeine in coffee bought from coffee shops. Brewed specialty coffees averaged 188 mg per 16 oz cup. More striking, the same drink bought from the same outlet on six consecutive days ranged from 259 to 564 mg per serving.

Coffee	Typical caffeine	Source
Regular brewed coffee, 12 oz	113 to 247 mg	FDA
Coffee-shop brewed coffee, 16 oz	Average 188 mg (58 to 259 mg range)	2003 lab study
Same 16 oz drink, same shop, six days	259 to 564 mg	2003 lab study
Decaf brewed coffee, 16 oz	0 to 13.9 mg	2006 lab study

Why Does Caffeine Vary So Much Between Cups?

Because caffeine depends on the bean, the amount of coffee used, the grind, the water temperature, the brew time, and the cup size. Small changes in any of those add up. That's why two cups that look identical can deliver very different doses, even from the same shop on different days.

The International Society of Sports Nutrition (ISSN) position stand on coffee and sports performance describes coffee as a complex mix whose contents vary "based upon serving size, bean type (e.g. common Arabica vs. Robusta), and brew method (water temperature, roasting method, grind size, time, and equipment)."

Of those, the amount of coffee and the cup size usually matter most for the caffeine in a cup of coffee made at home. Using an extra scoop or pouring a bigger mug has a far larger effect than most other tweaks. If you want a steady daily dose, measure your coffee the same way every time.

Does Dark Roast Have More Caffeine Than Light Roast?

Slightly less, if anything. Roasting breaks down a small amount of caffeine, so lighter roasts tend to keep a bit more when measured by weight. But the difference is small compared with how much coffee you use and how you brew it. Roast is a flavor choice more than a caffeine choice.

A 2011 study in Food Chemistry roasted different coffee varieties to light, medium, and dark levels and measured their caffeine. Caffeine content was highest in a light roast and "exhibited a decrease with intensified roasting."

Our guide on whether dark roast has more caffeine explains the myth in more detail and why scoop size can reverse the result.

How Much Caffeine Is in Decaf Coffee?

Not zero, but very little. Lab tests of decaf brewed coffee found between 0 and about 14 mg in a 16 oz serving, and decaf espresso shots contained about 3 to 16 mg each. That's a fraction of regular coffee, but it can add up for people who need to avoid caffeine strictly.

The 2006 decaf study in the Journal of Analytical Toxicology tested decaf from several coffee shops. Ten samples from different outlets ranged from 0 to 13.9 mg per 16 oz. The authors cautioned that people who must restrict caffeine should know that decaf can still contain some.

For most people, decaf is a good way to keep a coffee habit in the evening without the sleep cost. If you take creatine at night, a decaf cup works well as a warm, caffeine-free way to mix it, as our guide on taking creatine before bed explains.

How Many Cups of Coffee a Day Is Safe?

For most healthy adults, up to about 400 mg of caffeine a day, which the FDA says is roughly two to three 12 oz cups. People who are pregnant, trying to conceive, breastfeeding, taking certain medications, or sensitive to caffeine should talk to their doctor about a lower limit. Teens should stay lower too; our guide on whether coffee stunts your growth has a body-weight table.

The FDA's guidance on caffeine notes that people vary in how sensitive they are and how quickly they break caffeine down. Because the caffeine in a cup of coffee varies so much, counting cups is only a rough guide. If you notice jitters, a racing heart, or poor sleep, that's a better signal to cut back than any number.

Timing matters as much as the total. Our guide on how long caffeine lasts covers why an afternoon cup can still affect your sleep.

How Much Coffee Should You Drink Before a Workout?

Research on performance usually uses about 3 to 6 mg of caffeine per kilogram of body weight, about an hour before exercise. The ISSN suggests that works out to roughly two to four cups of typical brewed coffee, depending on your size and sensitivity. Many people do well at the lower end.

The ISSN coffee position stand puts optimal dosing at about 16 to 32 oz of brewed coffee providing 3 to 6 mg/kg of caffeine, taken 60 minutes before exercise. It also notes that coffee "can serve as a vehicle for other dietary supplements."

That makes a consistent morning cup useful for more than energy. Iron Coffee has 200 mg of natural caffeine and 5 g of creatine monohydrate per serving, so the caffeine dose is known rather than guessed. Our guide on drinking coffee before a workout covers timing and dose by body weight.