How Much Caffeine Is in a Cup of Coffee?

Coffee caffeine varies by beans and brew

The amount of caffeine in a cup of coffee depends on the type of coffee you're drinking and the size of the cup you're using. For example, a cup of brewed caffeinated coffee can have anywhere between around 95 mg (8 ounces, or a small coffee mug) and 450 mg of caffeine (for a 20-ounce cup of lightly roasted beans).

These amounts of caffeine will affect different people in different ways, as well. Some people get a significant boost from one small, weak cup of coffee, but others need much more to feel any alertness benefit at all. In addition, caffeine has side effects, and the dose that comfortably wakes one person up in the morning could be far too much for another person, inducing anxiety and the jitters.

The amount of caffeine in a cup of coffee isn't an exact science. It can vary somewhat, even when you're buying your java at the same place each day.

That's because of natural variations in the coffee beans themselves, plus any differences in how those beans were roasted, ground, and brewed.

Here are the basics about how much caffeine is in a cup of coffee, plus some details on how caffeine might actually affect you. You should consider these numbers more of an estimate rather than an exact science.

common side effects of caffeine
Verywell / Emily Roberts

Amount of Caffeine in Coffee

The amount of caffeine in a cup of coffee varies between brands, varieties of coffee beans, and brewing techniques—that's why we refer to "weak coffee" and "strong coffee." But most basically, you can count on a small cup of decaf to have the least amount of caffeine and an extra-large cup of brewed coffee (especially a light roast) to have the most caffeine. The following caffeine information is provided by the USDA and reflects an average or minimum amount.

Caffeine in Coffee (and Other Beverages) by Type and Cup Size


1 oz.

8 oz.

12 oz.

16 oz.

20 oz.

Decaf coffee, instant


2.4 mg

3.6 mg

4.8 mg

6 mg

Decaf coffee, brewed


2.4 mg

3.6 mg

6 mg

Decaf espresso

0.3 mg





Instant coffee


62 mg

94 mg

124 mg

156 mg

Brewed coffee


96 mg or more

144 mg or more

192 mg or more

240 mg or more


64 mg





Black tea


48 mg

72 mg

96 mg

120 mg

Green tea


30 mg

43 mg

58 mg

72 mg




34 mg

47 mg

56 mg

There are some general principles you can follow on coffee and caffeine, regardless of whether you're trying to limit your caffeine or consume more of it.

Decaffeinated Coffee

For example, decaffeinated coffee generally contains the least amount of caffeine per cup of coffee. However, it's not always caffeine-free.

Testing shows that instant decaf brands such as Folgers and Nescafe contain between 0 and 3 mg of caffeine per eight-ounce cup. Brewed decaf typically contains anywhere from around 4 to 7 mg of caffeine per eight-ounce cup, and brewed espresso contains up to 16 mg of caffeine per one-ounce shot.

Note that Starbucks says its decaffeinated coffee contains much more caffeine than the average for decaf (15 mg for an 8-ounce "short" cup). However, University of Florida chemists tested Starbucks decaf and found it contained less than the company reported (6 mg to 6.7 mg in an 8-ounce serving). 

Instant Coffee

Beyond decaffeinated coffee, instant coffee has the least amount of caffeine for regular coffee. An eight-ounce cup has approximately 62 mg of caffeine.

Brewed Coffee

Brewed coffee's caffeine content starts at approximately 95 mg per eight-ounce cup and goes up from there. Surprisingly, coffee made from lighter roasts can contain slightly more caffeine than darker roasts, since they're a bit denser than beans that have been roasted for longer. However, the difference may not be noticeable.


Espresso is measured differently than regular coffee—in one-ounce shots instead of in cups. A shot of espresso can contain 63 mg or more of caffeine, depending on the type of coffee used and how it's prepared. Therefore, an espresso-based drink with two shots in it—for example, a typical medium-sized latte or cappuccino—will include at least 125 mg of caffeine (milk and sugar are caffeine-free, although they can add significant calories to your coffee).

Coffee vs. Tea and Soda

Coffee isn't the only beverage that has caffeine; tea and soda also contain the chemical, albeit at levels that are somewhat less than brewed coffee. For example, black tea offers 48 mg per cup, while a 12-ounce can of soda contains between 34 and 55 mg of caffeine, depending on the brand.

Effects of Caffeine

For most people, it's okay to consume up to 400 mg of caffeine per day (so, four 8-ounce cups of brewed coffee, for example, or three lattes containing two shots of espresso each). However, even if you stick below that guideline, you may find that too much caffeine leads to unpleasant side effects, including:

  • Shakiness and jittery, anxious feelings
  • Trouble sleeping (especially if you consume caffeine late in the day)
  • Headaches and dizziness
  • Dehydration (caffeine is a diuretic)
  • Rapid heart rate

Plenty of people drink coffee to improve their alertness and performance. However, the main problem with using caffeinated coffee to wake up and perform better is that you build a tolerance to it, meaning you have to drink more over time to get the same beneficial effects.

This may not be a good thing. In fact, one study showed that caffeine consumption led to "faster but not smarter" results on mental performance tests and that those who habitually drank lots of it experienced an "increase in anxiety/jitteriness that offset the benefit of decreased sleepiness."

The news isn't all bad: older coffee drinkers had a 10% to 15% lower rate of death than those who didn't drink coffee, according to a major study on diet and health that tracked more than 400,000 people over 10 years. The analysis, which excluded people with cancer, heart disease, and stroke, found that drinking two or more cups of coffee per day had this effect. Coffee drinking improved the risk of death from heart disease, respiratory disease, stroke, injuries and accidents, diabetes, and infections, but not the risk of death due to cancer.

Still, the study couldn't determine cause-and-effect for the lower risk of death, and it did not consider whether people were drinking regular or decaf coffee.

Who Should Avoid Caffeinated Coffee?

Although the caffeine in coffee is safe for most people in moderate quantities, there are people with certain health conditions who might need to limit it or to steer clear of it entirely. Those health conditions include:

  • Pregnancy: The American College of Obstetricians and Gynecologists recommends limiting caffeine to less than 200 mg daily.
  • Sleep disorders: Caffeine early in the day may be okay.
  • Migraine: Caffeine may trigger or worsen migraines, although research is unclear.
  • Anxiety: Caffeine can compound anxious feelings.
  • GERD: Caffeine may worsen gastroesophageal reflux disease.
  • Glaucoma: Drinking beverages with caffeine may lead to higher eye pressure.

If you have any of these conditions, you should talk to your doctor about whether you should drink caffeinated coffee or other caffeinated beverages.

Although caffeine can increase your heart rate, there's some evidence that people who consume more caffeine have fewer irregular heartbeats, or arrhythmias, long term. In addition, even though caffeine can cause a very short-lived spike in your blood pressure, studies show caffeine does not cause high blood pressure.

There are a few prescription medicines that interact with caffeine, so you may need to avoid caffeinated coffee (and other caffeinated beverages) if you're taking one of these drugs. They include:

  • Some antibiotics
  • Thyroid medications
  • Certain anti-seizure drugs
  • Some antidepressants and other drugs used to treat mental health conditions
  • Certain medications for asthma

If you've been prescribed a drug that might fall into one of these groups and you have questions about your caffeine intake, make sure to discuss the issue with your pharmacist or physician.

A Word From Verywell

The vast majority of people—some 85% of all Americans, according to one study—consume at least one caffeinated beverage per day, and coffee is the beverage of choice. In fact, the mean daily caffeine intake across the entire U.S. population was 165 mg, about the equivalent of two small cups of brewed coffee.

There's decent medical evidence that for most healthy adults, that much-caffeinated coffee is safe, and likely will give you a quick boost. However, if you want to cut back on the caffeine but still enjoy your coffee, you always can switch to decaf—just be aware that you'll still be getting a bit of caffeine in every cup.

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