How much caffeine is in a cup of coffee?
It depends mostly on how much coffee went into the cup. A typical 8 oz cup brewed at a 1:16 ratio uses about 15–17 g of coffee, and arabica beans are roughly 1% caffeine by weight, most of which ends up in the cup. That puts most home-brewed 8 oz cups at about 100–200 mg. Robusta beans carry roughly twice the caffeine: Adriana Farah's tables put arabica at 0.9–1.3% of the bean's weight and robusta at 1.5–2.5%. The calculator's Beans setting covers robusta and blends.
| Drink | Serving | Caffeine (estimate) |
|---|---|---|
| V60 | 8 oz, 17 g coffee | 115–210 mg |
| Chemex | 8 oz, 17 g coffee | 115–210 mg |
| Kalita Wave | 8 oz, 17 g coffee | 115–210 mg |
| French press | 8 oz, 18 g coffee | 105–195 mg |
| AeroPress | 8 oz, 20 g coffee | 110–200 mg |
| Drip machine | 8 oz, 16 g coffee | 105–195 mg |
| Cold brew | 16 oz, diluted 1:1 | 205–445 mg |
| Espresso | single shot (about 1 oz) | 60–75 mg |
| Double espresso, latte or cappuccino | two shots | 120–150 mg |
| Decaf | 8 oz (the FDA's typical range) | 2–15 mg |
Estimates for arabica at the Brew Guide's classic ratios, rounded to the nearest 5 mg; a stronger ratio or robusta beans push them up. Café cups are often larger and stronger. The FDA says decaf "typically has 2 to 15 milligrams in an 8-fluid-ounce cup," so it isn't caffeine free.
Does espresso have more caffeine than drip coffee?
Per sip, yes; per drink, usually not. A single shot holds about 63 mg in about an ounce (the USDA lists espresso at 212 mg per 100 g, which is 62.8 mg per fluid ounce, calculated), so it is far more concentrated, but an 8 oz cup of drip coffee carries more in total. A latte or cappuccino made with a double shot lands near 120–150 mg, close to a cup of drip.
How long caffeine stays in your body
The body clears caffeine at a steady proportional rate, measured as a half-life: the time it takes to clear half of it. Studies put the average at about 2.5 to 4.5 hours in adult men (Institute of Medicine, 2001) and 3.4 hours, with a range of 2 to 5, in men and non-pregnant women (Knutti, 1981); the authors of a 2025 sleep trial say "typically 3–6 hours." The calculator's typical setting, 5 hours, is the middle of its three settings (3, 5 and 8 hours) and sits at the slow end of those averages, so its bedtime figures lean high.
Smoking speeds clearance up. Oral contraceptives can double the half-life, and pregnancy slows it a lot: in one study it rose from 3 hours to 10.5 hours in the last four weeks of pregnancy, about 3½ times as long (Knutti, 1982). At the typical setting, a 200 mg coffee at 3 pm leaves around 100 mg in you at 8 pm and around 50 mg near 1 am, which is why an afternoon coffee can still matter at bedtime.
The calculator draws that curve for your day. It also allows for about 45 minutes for caffeine to be absorbed, so each drink rises before it falls. It is an illustration of the average pattern, not a measurement of your body.
How much is too much?
- Most adults: The FDA says, “For most adults, the FDA has cited 400 milligrams a day — that's about two to three 12-fluid-ounce cups of coffee — as an amount not generally associated with negative effects.”
- In one go: EFSA found single doses of up to 200 mg raise no safety concerns for healthy adults.
- Pregnancy: ACOG (Committee Opinion 462) says, “Moderate caffeine consumption (less than 200 mg per day) does not appear to be a major contributing factor in miscarriage or preterm birth. The relationship of caffeine to growth restriction remains undetermined.”
These are general figures. Sensitivity varies a lot, and some medicines and conditions change it; ask a doctor about your own case.
Related guides
- Caffeine in coffee: a complete guide
- How coffee is decaffeinated
- Ristretto and lungo shots
- Brew Guide: coffee, water and timing for any brewer
Sources
- U.S. Department of Agriculture, Agricultural Research Service, FoodData Central, SR Legacy, FDC ID 171891: Beverages, coffee, brewed, espresso, restaurant-prepared (2018): caffeine 212 mg per 100 g; a 1 fl oz serving (29.6 g) works out to 62.8 mg, calculated.
- Adriana Farah, Coffee Constituents, in Yi-Fang Chu (ed.), Coffee: Emerging Health Effects and Disease Prevention (Wiley-Blackwell, 2012), chapter 2: Table 2.1, p. 28, and Table 2.2, p. 38 (caffeine in arabica and robusta beans).
- U.S. Food and Drug Administration, Spilling the Beans: How Much Caffeine is Too Much?, consumer update, content current as of August 28, 2024 (the 400 mg figure and decaf's 2 to 15 mg); European Food Safety Authority, scientific opinion on the safety of caffeine (2015); American College of Obstetricians and Gynecologists, Committee Opinion No. 462: Moderate Caffeine Consumption During Pregnancy (2010, reaffirmed).
- Institute of Medicine, Caffeine for the Sustainment of Mental Task Performance (2001): ch. 2, pp. 26–29: a half-life of 2.5–4.5 hours in adult men given 4 mg/kg; oral contraceptives can double it.
- Knutti, Rothweiler and Schlatter, Effect of pregnancy on the pharmacokinetics of caffeine (European Journal of Clinical Pharmacology 21: 121–126) (1981): abstract: 3.4 hours (range 2–5) in men and non-pregnant women.
- Knutti, Rothweiler and Schlatter, The effect of pregnancy on the pharmacokinetics of caffeine (Archives of Toxicology Supplement 5: 187–192) (1982): abstract: 3 hours in non-pregnant women, 10.5 hours in the last four weeks of pregnancy.
- Gardiner et al., Dose and timing effects of caffeine on subsequent sleep: a randomized clinical crossover trial (Sleep 48: zsae230) (2025): half-life "typically 3–6 hours".
- JayArr Coffee, Coffee Knowledge Synthesis (seventeen sources): §15 caffeine absorption, §17 caffeine by brew method.