A standard 8-ounce cup of brewed coffee contains roughly 95 to 200 mg of caffeine. That wide range exists because “a cup of coffee” can mean very different things depending on the beans, the brewing method, the roast, and where you bought it. A 12-ounce tall from Starbucks, for example, packs 235 to 290 mg, while an 8-ounce cup of decaf still delivers about 7 mg.
What Counts as “a Cup”
The standard U.S. cup of coffee is 8 fluid ounces, or about 237 milliliters. But that’s smaller than what most people actually drink. A typical mug holds 12 ounces, and a large to-go cup is 16 ounces or more. Coffee shops reinforce the confusion: a Starbucks “tall” is 12 ounces, and their “grande” is 16. When you see caffeine figures quoted online, always check the serving size. A number like “95 mg per cup” usually refers to that 8-ounce baseline, so if your morning mug is closer to 16 ounces, you’re likely getting double.
Brewing Method Changes Everything
The way you make your coffee has a bigger effect on caffeine than most people realize. Standard drip coffee lands in the 95 to 200 mg range per 8-ounce cup. Espresso is far more concentrated, at roughly 60 mg per single ounce, but a typical shot is only 1 to 1.5 ounces. So a single espresso gives you about 60 to 90 mg total, less than a full mug of drip coffee.
Cold brew sits at around 12 to 13 mg per ounce. That means a 16-ounce glass of cold brew delivers roughly 200 mg of caffeine, putting it on the higher end compared to the same volume of hot drip coffee. The long steeping time (often 12 to 24 hours) compensates for the cold water, which on its own extracts caffeine more slowly.
Hotter water pulls caffeine out of coffee grounds faster. Research on extraction kinetics shows that brewing at boiling temperature releases caffeine rapidly, with concentration plateauing within about six minutes. Cold water still extracts caffeine, just at a fraction of the speed, which is why cold brew compensates with such a long steep.
Arabica vs. Robusta Beans
Most specialty and grocery-store coffee is made from Arabica beans, which contain about 1.5% caffeine by weight. Robusta beans contain roughly 2.7%, nearly double. In practical terms, a 12-ounce cup brewed from Arabica beans has about 98 mg of caffeine, while the same size cup from Robusta beans has an estimated 190 mg. If your coffee tastes particularly strong or bitter and you’re feeling more wired than usual, Robusta beans (common in some instant coffees and espresso blends) could be the reason.
Light Roast vs. Dark Roast
There’s a persistent belief that dark roasts are “stronger” in caffeine. The reality is more nuanced. Light-roasted beans retain slightly more caffeine because the roasting process causes some caffeine to break down (sublimate) at higher temperatures. But darker roasts are more porous, meaning water can penetrate the grounds more easily and pull out what caffeine remains.
The net result: medium roasts often hit the sweet spot for caffeine in your cup. They’ve lost less caffeine to roasting than dark roasts, and their increased porosity compared to light roasts makes extraction more efficient. The difference between roast levels is real but modest. You won’t get twice the caffeine by switching from dark to light.
Chain Coffee Shop Caffeine Levels
Chain coffee varies more than you’d expect. A 12-ounce tall brewed coffee from Starbucks contains 235 to 290 mg of caffeine, which is significantly higher than the 95 mg baseline often quoted for a “cup of coffee.” Their espresso-based drinks contain less: a tall latte or cappuccino has about 75 mg (one shot of espresso), and a tall caffè mocha runs 90 to 95 mg. The brewed drip coffee is consistently the highest-caffeine option on the menu, not the espresso drinks.
This is worth knowing if you’re trying to manage your intake. Ordering a latte instead of a drip coffee at Starbucks cuts your caffeine by roughly two-thirds.
Decaf Still Contains Caffeine
Decaffeination removes at least 97% of the caffeine from coffee beans, but it doesn’t eliminate all of it. An 8-ounce cup of decaf contains about 7 mg on average. That’s a small amount for most people, but it’s not zero. If you’re highly sensitive to caffeine or drinking several cups of decaf a day, it can add up.
How Much Is Safe to Drink
The FDA considers 400 mg of caffeine per day safe for most healthy adults. That works out to roughly two to three 12-ounce cups of brewed coffee, depending on strength. A 2017 systematic review confirmed the safety of this 400 mg threshold. Going above it doesn’t guarantee problems, but side effects like anxiety, insomnia, a racing heartbeat, and digestive issues become more likely.
If you’re drinking a large Starbucks drip coffee (a 16-ounce grande could push past 300 mg), you’re already using up most of that daily budget in a single cup. Adding a second coffee, a tea, or a caffeinated soda later in the day could push you over. Knowing your actual milligram intake, rather than just counting “cups,” is the more useful way to track it.
Quick Caffeine Comparison
- 8 oz drip coffee (Arabica): 95 to 200 mg
- 12 oz Starbucks tall brewed: 235 to 290 mg
- Single espresso shot (1 oz): ~60 mg
- 16 oz cold brew: ~200 mg
- 12 oz Robusta brewed coffee: ~190 mg
- 8 oz decaf: ~7 mg
- FDA daily limit for adults: 400 mg