Your total against the 400 mg line
Add up the caffeine from everything you drink and compare it to the FDA’s 400 mg per day guideline for healthy adults. It is a daily total, not per-drink — small amounts from tea, soda and chocolate stack up alongside coffee.
Caffeine in common drinks
| Drink | Serving | Caffeine |
|---|---|---|
| Espresso | 1 shot (30 ml) | 63–75 mg |
| Brewed coffee | 8 oz (240 ml) | 95–165 mg |
| Black tea | 8 oz (240 ml) | 25–50 mg |
| Green tea | 8 oz (240 ml) | 15–30 mg |
| Energy drink | 8 oz (240 ml) | 50–160 mg |
| Cola | 12 oz (355 ml) | 34–46 mg |
| Milk chocolate | 1.5 oz (45 g) | 5–10 mg |
Ranges are wide because brew strength, cup size and brand all vary. Decaf is not zero — it keeps about 2 to 12% of the original, or a few milligrams per cup.
Limits worth knowing
- Healthy adults. Up to 400 mg a day (FDA and EFSA), and no more than about 200 mg in one sitting.
- Pregnancy. 200 mg a day or less — caffeine clears two to four times more slowly and reaches the fetus.
- Teens and children. Health bodies advise avoiding energy drinks and keeping intake very low; there is no established safe amount.
- Timing matters. With a ~5-hour half-life, caffeine after early afternoon can still be in your system at bedtime.
Common questions
How much caffeine per day is safe?
The FDA points to 400 mg a day as the amount most healthy adults can consume without harmful effects. That is roughly four 8-ounce cups of brewed coffee. The EFSA in Europe uses the same 400 mg daily figure, plus a 200 mg single-dose guideline.
How much caffeine is in a cup of coffee?
A standard 8-ounce cup of brewed coffee has about 95 to 165 mg. A single espresso shot is 63 to 75 mg, black tea is 25 to 50 mg, and most energy drinks run 50 to 300 mg per can depending on size and brand.
How long does caffeine stay in your system?
Caffeine has a half-life of about 5 hours in a typical adult, so half is gone in 5 hours, a quarter remains after 10, and it is essentially cleared after roughly 16 to 17 hours. That is why an afternoon coffee can still disturb sleep.
Is the safe limit lower during pregnancy?
Yes. Health authorities including the WHO advise keeping intake at or below 200 mg a day during pregnancy, because caffeine clears far more slowly and crosses to the fetus. That is about one to two cups of coffee.
