The limits
| Who | Upper amount | Source |
|---|---|---|
| Healthy adults | 400 mg a day | FDA, EFSA |
| Healthy adults, in one dose | 200 mg | EFSA |
| Pregnant or breastfeeding | 200 mg a day | EFSA |
| Children and teens | 3 mg per kg of body weight a day | EFSA |
The FDA cites 400 mg a day for most adults, about two to three 12 oz cups of coffee, as an amount not generally associated with negative effects (FDA). The European Food Safety Authority set the same daily figure in 2015, about 5.7 mg per kg of body weight, for caffeine spread through the day. It added three more: single doses up to 200 mg raise no safety concern for healthy adults, up to 200 mg a day raises no concern for the foetus in pregnancy, and children and teens should stay under 3 mg per kg of body weight a day (EFSA). For a 50 kg (110 lb) teenager, that is 150 mg.
The FDA recommends that anyone who is pregnant, trying to get pregnant or breastfeeding talks to their health care provider about caffeine.
What 400 mg looks like
How many servings of common drinks reach 200 mg, the single-dose figure, and 400 mg, the daily figure. Serving sizes and caffeine amounts are the defaults in the WaterChamp app.
| Drink | Caffeine | Servings to 200 mg | Servings to 400 mg |
|---|---|---|---|
| Cold Brew | 200 mg | 1.0 | 2.0 |
| Iced Coffee | 165 mg | 1.2 | 2.4 |
| Drip Coffee | 140 mg | 1.4 | 2.9 |
| Flat White | 126 mg | 1.6 | 3.2 |
| Black Coffee | 95 mg | 2.1 | 4.2 |
| Energy Drink | 80 mg | 2.5 | 5.0 |
| Matcha Latte | 70 mg | 2.9 | 5.7 |
| Espresso | 63 mg | 3.2 | 6.3 |
| Black Tea | 47 mg | 4.3 | 8.5 |
| Diet Soda | 46 mg | 4.3 | 8.7 |
| Cola | 33 mg | 6.1 | 12.1 |
| Green Tea | 30 mg | 6.7 | 13.3 |
One 12 oz cold brew reaches 200 mg on its own. Four 8 oz cups of brewed coffee come to 380 mg. It takes about 12 cans of cola to reach 400 mg.
Signs of too much caffeine
The FDA lists these effects of too much caffeine: a faster heart rate, heart palpitations, high blood pressure, insomnia or disrupted sleep, anxiety, jitters, an upset stomach, nausea and headache (FDA). Rapid intake of around 1,200 mg, less than half a teaspoon of pure caffeine, can cause toxic effects such as seizures. The FDA warns that pure and highly concentrated caffeine products can have serious health consequences, including death.
The same amount affects people differently
People vary widely in how sensitive they are to caffeine and in how fast they eliminate it (FDA). A single 100 mg dose may affect sleep in some adults, particularly close to bedtime (EFSA). See how long caffeine lasts for the hour-by-hour numbers, or check your own day in the caffeine calculator. The app starts with a 400 mg daily limit, and you can change it.
Questions
Is 200 mg of caffeine a lot?
It is EFSA's figure for a single dose in healthy adults, and for a whole day in pregnancy. A 12 oz cold brew or two 8 oz cups of brewed coffee come to about 200 mg.
How many cups of coffee a day is too many?
For most healthy adults, more than about four 8 oz cups of brewed coffee a day goes past the FDA's 400 mg. Espresso drinks count by the shot, about 63 mg each.
Is 400 mg of caffeine too much for a teenager?
It is far above EFSA's level for children and teens, 3 mg per kg of body weight a day, which is 150 mg for a 50 kg (110 lb) teenager. The FDA notes that medical experts advise against energy drinks for children and teens.
What happens if you have too much caffeine?
The FDA lists a faster heart rate, palpitations, high blood pressure, poor sleep, anxiety, jitters, an upset stomach, nausea and headache. Rapid intake of around 1,200 mg can cause seizures.
