A standard 8-ounce cup of brewed coffee contains about 96 milligrams of caffeine. That number shifts depending on the type of coffee, the beans, the roast, and how you brew it, so your actual intake could range anywhere from 50 to 200 mg in a single cup.
Caffeine by Coffee Type
Not all coffee is created equal when it comes to caffeine. Here’s how the most common types compare:
- Drip-brewed coffee: 96 mg per 8 oz
- Espresso: about 63 mg per 1-oz shot (range of 30 to 100+ mg)
- Instant coffee: roughly 57 mg per 6-oz cup
- Cold brew: about 200 mg per 16 oz
- Decaf: up to 7 mg per 8 oz
Cold brew often surprises people. A 16-ounce glass packs around 200 mg, which is comparable to hot drip coffee of the same size. Despite using more coffee grounds, cold brew actually extracts slightly less caffeine than hot water does. At Starbucks, for instance, a 16-ounce cold brew has 205 mg while the same size hot coffee ranges from 210 to 360 mg.
Espresso is the most concentrated form of coffee by volume, but because the serving size is so small, a single shot delivers less total caffeine than a full mug of drip coffee. A double-shot latte, then, contains roughly 126 mg, still less than a 12-ounce pour of regular brewed coffee.
Why Your Cup Size Matters More Than You Think
One confusing detail: a “cup” on your coffee maker is not the same as a standard measuring cup. Most coffee machine manufacturers define one cup as 6 fluid ounces, not 8. So if your machine says it brews 12 cups, you’re getting about 72 ounces, not 96. Meanwhile, the mugs most people drink from hold 12 to 16 ounces, meaning a single mug of drip coffee could easily contain 150 to 190 mg of caffeine.
When you see caffeine data listed “per cup,” check whether it means 6, 8, or 12 ounces. That distinction alone can double your actual caffeine intake compared to what you assumed.
Arabica vs. Robusta Beans
The two main species of coffee beans have very different caffeine levels. Arabica beans, which make up the majority of specialty and grocery store coffee, contain about 1.2 to 1.5% caffeine by dry weight. Robusta beans pack nearly twice as much, at 2.2 to 2.7%.
Most name-brand and single-origin coffees use Arabica. Robusta shows up more often in budget blends, instant coffee, and some espresso blends where a stronger, more bitter flavor is intentional. If you’re drinking a Robusta-heavy blend, your per-cup caffeine could be significantly higher than the typical 96 mg figure.
Light Roast vs. Dark Roast
There’s a persistent idea that dark roast coffee is “stronger” in caffeine. The reality is more nuanced. When measured by weight (grams of ground coffee), light and dark roasts contain very similar amounts of caffeine. One study found that a serving of light roast brewed coffee had about 60 mg of caffeine, while the same weight of dark roast had 51 mg, a small difference that varies between batches.
The confusion comes from how you scoop your coffee. Dark roast beans puff up during roasting and become less dense, so a tablespoon of dark roast weighs less than a tablespoon of light roast. If you measure by the scoop, light roast ends up with slightly more caffeine per cup simply because you’re using more coffee by weight. If you measure by weight on a kitchen scale, the two roasts are nearly identical. In practical terms, the difference is small enough that it shouldn’t drive your choice of roast.
How Decaf Compares
Decaf is not caffeine-free. An 8-ounce cup of decaf brewed coffee contains up to 7 mg of caffeine, and larger servings increase that proportionally. A 16-ounce decaf from a coffee shop averages around 9.4 mg, with individual shops ranging from about 8.6 to 13.9 mg. Decaf espresso shots contain 3 to 15.8 mg each. Decaf instant coffee has the least, at roughly 3 to 4 mg per standard serving.
For most people, these amounts are negligible. But if you’re highly sensitive to caffeine or avoiding it for medical reasons, those milligrams can add up over several cups.
How Much Is Safe Per Day
The FDA considers up to 400 mg of caffeine per day safe for most healthy adults. That works out to roughly four 8-ounce cups of brewed coffee, or about two to three 12-ounce mugs. Going beyond that threshold increases the likelihood of side effects like restlessness, insomnia, a racing heartbeat, and digestive discomfort.
Tolerance varies widely from person to person, largely based on genetics, body weight, and how regularly you consume caffeine. Some people feel jittery after a single cup, while others can drink three with no noticeable effect. Pregnancy, certain medications, and heart conditions can all lower your safe threshold well below 400 mg.