A standard 8-ounce cup of brewed coffee contains about 96 milligrams of caffeine. That’s the average, but the real number in your cup can range anywhere from roughly 60 to 150 milligrams depending on the beans, the roast, and how you brew it. Understanding what shifts that number helps you gauge your actual daily intake.
Caffeine by Brewing Method
The way you make your coffee changes how much caffeine ends up in your cup more than almost any other factor. Hotter water and longer contact time pull more caffeine out of the grounds, which is why different methods produce such different results.
Espresso is the most concentrated method, extracting roughly 4,200 milligrams of caffeine per liter of liquid. But a single espresso shot is only about 30 milliliters (one ounce), so you’re getting around 63 milligrams per shot. That’s actually less caffeine than a full mug of drip coffee, even though it tastes much stronger. A University of Newcastle study ranked extraction strength across methods and found cold brew came in second at 2,240 milligrams per liter, followed closely by stovetop (moka pot) brewing at 2,192 milligrams per liter. French press and pour-over were significantly lower, at 742 and 692 milligrams per liter respectively.
What matters in practice is serving size. A typical pour-over cup is around 250 milliliters (about 8.5 ounces), so despite its lower concentration, you end up drinking a decent amount of caffeine. A cold brew concentrate served at 60 milliliters delivers roughly 134 milligrams before dilution. Once you factor in the water or milk most people add, a 12-ounce cold brew drink typically lands between 109 and 285 milligrams of caffeine, with large servings reaching 300 milligrams or more.
Arabica vs. Robusta Beans
The species of coffee bean in your bag makes a significant difference. Arabica beans, which account for the majority of specialty and grocery store coffee, contain about 1.5% caffeine by weight. Robusta beans contain roughly 2.7%, nearly double. If your coffee blend includes Robusta (common in instant coffee, some espresso blends, and many store-brand ground coffees), your cup will have noticeably more caffeine than a pure Arabica brew.
Light Roast vs. Dark Roast
There’s a persistent idea that dark roast coffee is “stronger” and therefore higher in caffeine. The reality is more nuanced. When measured by weight (grams of coffee), light and dark roasts contain very similar amounts of caffeine. One study found light roast brewed coffee had about 60 milligrams per serving compared to 51 milligrams for the same amount of dark roast, a small difference that can vary between batches.
The confusion comes from how people measure their coffee. Dark roast beans puff up during roasting and become less dense. If you scoop your coffee by volume (tablespoons), you’ll use fewer beans per scoop with a dark roast, which means slightly less caffeine. If you weigh your coffee on a kitchen scale, the difference between roasts essentially disappears. For most people scooping from a bag each morning, light roast will deliver marginally more caffeine per cup.
Caffeine at Major Coffee Chains
Coffee shop drinks can vary wildly from what you’d brew at home. A 12-ounce (tall) brewed coffee at Starbucks contains between 235 and 290 milligrams of caffeine. That’s roughly two and a half times the caffeine in a home-brewed 8-ounce cup, partly because Starbucks uses a higher coffee-to-water ratio and a larger serving size.
Espresso-based drinks at the same chain are a different story. A 12-ounce latte or cappuccino at Starbucks has only about 75 milligrams, since it’s built on a single shot of espresso diluted with steamed milk. A flat white bumps that up to around 130 milligrams with its extra shot, while a caffè mocha lands at 90 to 95 milligrams. The takeaway: a “plain coffee” from a chain often packs far more caffeine than a latte or specialty drink.
What About Decaf?
Decaf isn’t caffeine-free. An 8-ounce cup of decaffeinated coffee still contains about 7 milligrams of caffeine. That’s a small fraction of regular coffee, but it can add up if you’re drinking several cups, especially if you’re trying to avoid caffeine entirely for health reasons.
How Much Is Safe to Drink
The FDA considers up to 400 milligrams of caffeine per day safe for most healthy adults. That works out to roughly four 8-ounce cups of home-brewed coffee, or about two 12-ounce cups from a chain like Starbucks. Most people can stay comfortably within that range without thinking about it, but if you’re drinking large cold brews or high-volume servings, it’s easier to overshoot than you might expect.
During pregnancy, the threshold is lower. The American College of Obstetricians and Gynecologists recommends keeping caffeine under 200 milligrams per day, noting that moderate intake below that level does not appear to increase the risk of miscarriage or preterm birth. That’s roughly two home-brewed cups, or one tall drip coffee from a chain.
Why Your Cup Varies So Much
Caffeine extraction depends on water temperature, brew time, grind size, and coffee-to-water ratio, all working together. Water between 90°C and 100°C (194°F to 212°F) extracts caffeine most efficiently, pulling up to 90% of the available caffeine from the grounds when brewed for about 15 minutes. Most drip machines brew for less time than that, which is one reason home coffee tends to be moderate in caffeine rather than maxed out.
Grind size matters because finer grounds expose more surface area to water, speeding up extraction. This is why espresso, which uses very fine grounds and pressurized hot water, extracts so much caffeine per milliliter despite such short contact time. French press coffee, by contrast, uses coarse grounds and steeps for four to five minutes, resulting in a lower concentration. If you’re trying to control your caffeine intake, adjusting your brew time, water temperature, or grind size gives you more leverage than switching roasts.