How Much Caffeine Is in a Cup of Coffee?

Coffee caffeine varies by beans and brew

The energy burst we get from coffee comes from the stimulant caffeine, which activates adrenaline in the body. Caffeine itself is a bitter-tasting, adrenaline-stimulating compound that is found naturally in a variety of plants. Many people seek out caffeinated beverages specifically for that adrenaline buzz. But exactly how much caffeine is in each cup of joe, and how much is healthy to consume each day?

Overview

Determining how much caffeine is in your coffee is not as straightforward as you might think. You need to weigh a wide variety of factors, including the type of coffee bean, how it was brewed, and the size of the cup you're using.

A cup of brewed caffeinated coffee can have anywhere from around 65 milligrams (mg) to 175mg of caffeine or all the way up to 450mg of caffeine for larger servings. Espresso has around twice the concentration of caffeine as brewed coffee but is generally consumed in smaller quantities. Additionally, various quantities of caffeine will affect different people in different ways.

Caffeine Tolerance

Some people get a significant boost from one small, weak cup of coffee, while others need much more to feel any spike in alertness. Plus, 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 jitters.

Not only does the amount of caffeine in a cup of coffee vary from cup to cup but people each have their own caffeine tolerance level, which will increase as you increase the quantity you consume over time.

Plus, even if you drink the same coffee day after day, the amount of caffeine in it can change. That's because of natural variations in the coffee beans themselves, plus any differences in how those beans were roasted, ground, and brewed.

Read on for details on approximately how much caffeine is in a cup of coffee. Plus, we review how caffeine might affect you.

common side effects of caffeine
Verywell / Emily Roberts

Amount of Caffeine in Coffee

The exact amount of caffeine that's in a cup of coffee ranges quite a bit between brands, varieties of coffee beans, and brewing techniques—that's why we refer to the possibility of making "weak coffee" or "strong coffee."

Generally, 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 you can expect to find in each size and type of coffee.

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

 

1 oz.

8 oz.

12 oz.

16 oz.

20 oz.

Decaf coffee, instant

 

2.4mg

3.6mg

4.8mg

6mg

Decaf coffee, brewed

 

2.4mg

3.6mg

4mg

6mg

Decaf espresso

0.3mg

 

 

 

 

Instant coffee

 

62mg

94mg

124mg

156mg

Brewed coffee

 

96mg or more

144mg or more

192mg or more

240mg or more

Espresso

64mg

 

 

 

 

Black tea

 

48mg

72mg

96mg

120mg

Green tea

 

30mg

43mg

58mg

72mg

Soda

 

 

34mg

47mg

56mg

The following are some general principles that can help guide your coffee choices whether you're trying to limit your caffeine or consume more of it.

Decaffeinated Coffee

Decaffeinated coffee generally contains the least amount of caffeine per cup of all coffee products. However, it's not always completely caffeine-free.

Testing shows that instant decaf brands such as Folgers and Nescafe contain between 0mg and 3mg of caffeine per 8-ounce cup. So, if you're looking to greatly limit your caffeine, those are good options. Brewed decaf typically contains anywhere from around 4mg to 7mg of caffeine per 8-ounce cup, and brewed espresso contains up to 16mg of caffeine per 1-ounce shot.

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

Instant Coffee

After decaffeinated coffee, instant coffee has the least amount of caffeine for regular coffee. An 8-ounce cup has approximately 62mg of caffeine.

Brewed Coffee

Brewed coffee's caffeine content starts at approximately 95mg per 8-ounce cup and goes up from there. Surprisingly, coffee made from lighter roasts contain slightly more caffeine than darker roasts. Lighter roasted beans are a bit denser than beans that have been roasted for longer at higher temperatures.

Generally, the longer (and darker) the beans are roasted, the more caffeine is lost in the process. However, the difference in caffeine may not be noticeable, while the difference in flavor is—darker roasts tend to have a richer flavor.

Espresso

Espresso is measured differently than regular coffee—in 1-ounce shots rather than in cups. A shot of espresso can contain 63mg or more of caffeine, depending on the type of coffee used and how it's prepared.

So, an espresso-based drink with two shots in it—for example, a typical medium-sized latte or cappuccino—will include at least 125mg of caffeine (added milk and sugar are caffeine-free, although they will add calories to your coffee).

Iced Coffee

Iced coffee drinks will have the same caffeine as the hot version of whichever coffee is used to make it. However, since it's poured over ice, which takes up space and melts into the drink, you'll end up with a slightly less caffeinated beverage overall compared to the same sized cup of hot coffee with no additions.

Serving Size

When estimating a drink's caffeine content, it's important to keep in mind that many coffee shops, Starbucks included, sell coffee drinks in multiple portion sizes—most of which are much larger than the typical 8-ounce serving. So, sometimes, your one "cup" of coffee might actually be worth two or more in terms of caffeine (and calories).

Bean Strength

Caffeine content varies across different types of coffee beans and even individual coffee plants. For example, the popular Arabica beans are known for their superior flavor but pack a lower caffeine jolt than the Robusta variety. Plus, some coffee is made from "blends" or a mix of beans.

Coffee vs. Tea and Soda

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

Effects of Caffeine

Caffeine is a mild psychoactive drug that occurs naturally in coffee, tea, and cacao plants and is added to many other products, such as sodas and energy drinks. It works by activating the central nervous system, which causes an increase in alertness and energy by stimulating a rush of adrenalin.

Caffeine molecules also reduce sleepiness by binding to the brain's adenosine receptors, a neurotransmitter that causes feelings of tiredness. About 20 minutes after drinking a cup of coffee, you'll start to notice a caffeine boost. At around an hour later after your first sip, you'll experience the drink's full effect.

For most people, it's OK to consume up to 400mg of caffeine per day. This translates to a maximum of about four 8-ounce cups of brewed coffee, for example, or three lattes containing two shots of espresso each. However, even if you consume less caffeine than that guideline and certainly if you drink more, you may find that your caffeine intake leads to unpleasant side effects, including:

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

Why People Drink It

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 and more over time to get the same effects. This may not always 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."

However, most adults ritually drink coffee each day and swear by its ability to help them wake up and keep them feeling energized.

Health Benefits

Many studies have shown coffee to have positive health benefits. According to a major study on diet and health that tracked more than 400,000 people over 10 years, older coffee drinkers were found to have a 10% to 15% lower rate of death than those who didn't drink coffee.

The analysis, which excluded people with cancer, heart disease, and stroke, found that drinking two or more cups of coffee per day was linked with greater longevity. Coffee drinking decreased 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.

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. Research also points to possible stress relief properties of caffeine.

Health Risks

Although the caffeine in coffee is usually safe in moderate amounts, there are people with certain health conditions who may benefit from limiting or eliminating caffeine consumption. Those health conditions include:

  • Pregnancy: The American College of Obstetricians and Gynecologists (ACOG) recommends limiting caffeine to less than 200mg daily during pregnancy.
  • Sleep disorders: Caffeine is known to worsen sleep and it is generally recommended that people who struggle with sleep limit or avoid caffeine—though consumption early in the day may be OK for some.
  • Migraine: Caffeine may trigger or worsen migraines, although research is unclear.
  • Anxiety: Caffeine can compound anxious feelings.
  • Gastroesophageal reflux disease (GERD): Caffeine may worsen symptoms of gastroesophageal reflux disease.
  • Glaucoma: Drinking beverages with caffeine may exacerbate 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.

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

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

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 American adults, according to one study—consume at least one caffeinated beverage per day, and coffee is often the beverage of choice. In fact, the mean daily caffeine intake across the entire United States population was 165mg, which is about the equivalent of two small cups of brewed coffee.

There's decent medical evidence that for most healthy adults, modest intake of caffeinated coffee is safe—and likely to give you a quick boost when you need it. However, if you want to cut back on the caffeine but still enjoy your coffee, you always can switch to decaf, which has much less caffeine per cup.

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