A 12-ounce cup of brewed coffee contains roughly 120 to 150 milligrams of caffeine. That number shifts depending on the type of bean, how finely it’s ground, and how it’s brewed, but for standard drip coffee, that range covers most cups you’ll pour at home or pick up at a café. An 8-ounce cup averages about 96 mg, so scaling up to 12 ounces lands you in that neighborhood.
Why the Number Varies So Much
Coffee isn’t a standardized product the way a soda or energy drink is. Two cups brewed from different beans in different machines can easily differ by 50 mg or more. The main factors that push caffeine up or down are bean variety, roast level, grind size, water temperature, and brew time.
Robusta beans contain nearly twice the caffeine of Arabica beans, which are the most commonly sold variety. Light roasts retain slightly more caffeine than dark roasts, though the difference is small enough that most people won’t notice. What matters more is how long hot water stays in contact with the grounds. A longer brew time extracts more caffeine, which is why cold brew (steeped for 12 to 24 hours) tends to be significantly stronger than a quick pour-over.
Caffeine by Brewing Method
Drip or filter coffee lands in the range of 95 to 165 mg per 8-ounce serving, which translates to roughly 140 to 250 mg for 12 ounces depending on strength. French press coffee averages about 107 mg per 8 ounces, putting a 12-ounce cup around 160 mg. The difference comes down to how thoroughly the water saturates the grounds and whether a paper filter absorbs some of the extracted compounds.
Espresso is a different story. A single shot (about 1 ounce) packs around 63 mg of caffeine. A 12-ounce latte typically contains one or two shots, so you’re looking at 63 to 126 mg total, with the rest of the cup being steamed milk. Ounce for ounce, espresso is far more concentrated than drip coffee, but because lattes use so little of it relative to the cup size, a 12-ounce latte actually delivers less caffeine than a 12-ounce drip coffee in most cases.
How Decaf Compares
Decaf isn’t caffeine-free. The decaffeination process removes about 97% of the caffeine, leaving a small residual amount. A 12-ounce cup of decaf brewed coffee typically contains 7 to 8 mg of caffeine. That’s low enough to be negligible for most people, but it’s worth knowing if you’re extremely sensitive or drinking several cups.
The amount varies by brand. Starbucks decaf (Pike Place Roast) contains around 20 mg per 10 to 12 ounce cup, noticeably higher than Dunkin’ Donuts decaf at about 7 mg or McDonald’s at 8 mg. Instant decaf coffee falls even lower, at 3 to 4 mg per serving.
How This Fits Into Daily Limits
The FDA considers 400 mg of caffeine per day a safe upper limit for most healthy adults. That’s roughly two to three 12-ounce cups of regular brewed coffee, depending on strength. Going above 400 mg doesn’t guarantee problems, but it increases the likelihood of jitteriness, disrupted sleep, a racing heartbeat, or an upset stomach.
Pregnancy, certain medications, and individual sensitivity can lower that threshold considerably. Oral contraceptives, for example, can double the time it takes your body to clear caffeine, meaning the same cup hits harder and lasts longer.
How Long Caffeine Stays in Your System
Caffeine’s half-life in the body averages about 5 hours, meaning that if your 12-ounce cup delivered 140 mg at noon, you’d still have roughly 70 mg circulating at 5 PM. The full range is wider than most people expect: anywhere from 1.5 to 9.5 hours depending on genetics, body composition, smoking status, and hormonal factors.
This is why the same afternoon coffee that barely registers for one person keeps another up past midnight. Smokers metabolize caffeine roughly twice as fast as nonsmokers, while people taking oral contraceptives or those who are pregnant process it much more slowly. If you find that coffee affects your sleep, the timing of your last cup matters more than the total amount you drink in a day.