A 12-ounce cup of brewed coffee contains roughly 113 to 247 milligrams of caffeine, with most standard cups landing somewhere around 120 to 160 mg. That’s a wide range, and the exact number depends on the beans, the roast, how strong you brew it, and where you buy it.
Why the Range Is So Wide
The single biggest factor is how much ground coffee goes into the brew. More grounds per cup means more caffeine extracted into your drink. A light, watery cup from a hotel lobby and a rich, strong pour from your favorite café can differ by over 100 mg even though they’re the same volume.
Bean variety matters too. Most specialty and grocery store coffee is Arabica, which contains less caffeine than Robusta beans. Robusta has roughly twice the caffeine content of Arabica, so blends that include Robusta (common in some instant coffees and espresso blends) will push that number higher.
Roast level plays a smaller but real role. Lighter roasts retain slightly more caffeine than darker roasts because the longer roasting process breaks down a small amount of the caffeine. The difference isn’t dramatic, but if you’re comparing a light roast to a very dark French roast brewed at the same ratio, the lighter roast will edge ahead.
Caffeine at Major Coffee Chains
Chain coffee shops are where most people encounter a 12-ounce cup, and the differences between brands are surprisingly large. Starbucks is notably higher in caffeine than most competitors. A 12-ounce Tall brewed coffee from Starbucks contains 235 to 290 mg of caffeine. That’s nearly double what you’d get from a home-brewed cup using Folgers Classic Roast, which runs about 120 to 160 mg for the same 12 ounces.
Starbucks uses a higher coffee-to-water ratio and specific bean blends that drive their caffeine content up. If you’re trying to moderate your intake, this is worth knowing: two Tall Starbucks coffees could put you at or above the daily limit most health agencies recommend, while two cups of typical home-brewed coffee would still leave you well under it.
If you want to cut your caffeine without giving up the ritual, half-caff blends like Folgers 1/2 Caff deliver about 60 to 80 mg per 12 ounces. Decaf isn’t truly caffeine-free either. A 12-ounce cup of decaf typically contains 2 to 8 mg.
Does Brewing Method Change the Number?
Less than you might think. Caffeine is one of the first compounds extracted from coffee grounds, so the amount in your cup correlates strongly with the dose of coffee you start with. If you use 15 grams of ground coffee, you’ll get a similar caffeine output whether you brew it as a drip, pour-over, or French press.
That said, the methods aren’t perfectly identical. A French press lets grounds steep in water for several minutes, which can increase overall extraction. A pour-over constantly introduces fresh water, which also has the potential to pull out slightly more caffeine when brewed for high extraction. In practice, these differences are modest compared to simply using more or fewer grounds. The ratio of coffee to water is the lever that moves your caffeine content the most.
How Much Is Safe Per Day
The FDA cites 400 mg per day as the amount not generally associated with negative effects for healthy adults. That works out to about two to three 12-ounce cups of typical brewed coffee. A 2017 systematic review confirmed the safety of that 400 mg threshold for most people.
At a practical level, this means if you’re drinking standard home-brewed coffee at around 140 mg per cup, you can comfortably have two to three cups a day. If you’re drinking Starbucks, you’re closer to your limit after just one or two Tall servings.
How Caffeine Moves Through Your Body
After you drink your coffee, caffeine reaches peak levels in your bloodstream after about 60 minutes. Its half-life, the time it takes your body to eliminate half of it, generally ranges from 4 to 6 hours. So if you drink a 12-ounce cup with 150 mg of caffeine at noon, you’ll still have roughly 75 mg circulating at 4 to 6 PM, and around 37 mg at bedtime if you go to sleep around 10.
This is why afternoon coffee can interfere with sleep even when you feel fine drinking it. The caffeine isn’t gone just because the alertness has worn off. If sleep quality matters to you, the half-life math suggests keeping your last cup before early afternoon.