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400 mg for most adults
That's about four 8-ounce cups of brewed coffee a day, according to the FDA.
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200 mg in pregnancy
About two cups of coffee a day from all sources, including tea, soda and chocolate.
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Watch the cup size
A 16-ounce coffee shop drink is two standard cups. A 20-ounce one is two and a half.
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Energy shots add up fast
One 2-ounce shot has about 215 mg, more than half the adult daily limit.
How many drinks reach the limit
Full servings you can have before going over each daily limit, using typical caffeine amounts. Brands and brewing vary, so treat these as rough guides.
Servings that stay within each limit
| Drink (caffeine) | Adult 400 mg | Pregnancy 200 mg | Teen 100 mg |
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| Brewed coffee, 8 oz (96 mg) | 4 | 2 | 1 |
| Espresso, 1 shot (64 mg) | 6 | 3 | 1 |
| Instant coffee, 8 oz (62 mg) | 6 | 3 | 1 |
| Black tea, 8 oz (47 mg) | 8 | 4 | 2 |
| Green tea, 8 oz (28 mg) | 14 | 7 | 3 |
| Cola, 12 oz can (33 mg) | 12 | 6 | 3 |
| Energy drink, 8 oz (72 mg) | 5 | 2 | Not advised |
| Energy shot, 2 oz (215 mg) | 1 | 0 | Not advised |
Why "too much" is different for everyone
The 400 mg figure is a general guide for healthy adults, not a target. The FDA notes that people differ a lot in how sensitive they are to caffeine and how fast their bodies clear it. Some medications and health conditions make caffeine a bigger concern, so if you have questions, ask your doctor or pharmacist.
Caffeine also hides in places you might not count: chocolate, some pain relievers, pre-workout powders and "decaf" coffee, which still has a few milligrams a cup. Pure powdered or liquid caffeine is the one to stay away from entirely, because a tiny scoop can be a dangerous dose.
Common questions
How much caffeine is too much in a day?
For most healthy adults, the FDA says up to 400 mg a day is not generally linked to harmful effects. People vary a lot in how sensitive they are, so less may be right for you, especially if you take certain medications or have a health condition.
How many cups of coffee is 400 mg of caffeine?
About four 8-ounce cups of brewed coffee, at roughly 96 mg each. A 16-ounce coffee shop drink counts as two cups, so two of those is already close to 400 mg.
How much caffeine is OK when pregnant?
The commonly advised limit during pregnancy is 200 mg a day from all sources, which is about two 8-ounce cups of brewed coffee. The FDA suggests talking with your health care provider if you're pregnant, trying to get pregnant or breastfeeding.
How much caffeine can teenagers have?
Pediatricians commonly advise teens ages 12 to 18 to stay under 100 mg a day, about one cup of coffee, and children under 12 to avoid caffeine. Energy drinks are not recommended for children or teens.
What are the signs of too much caffeine?
The FDA lists jitters, feeling anxious, a fast heart rate, an upset stomach, headache and trouble sleeping. If you notice these, cut back. Pure powdered or liquid caffeine is especially dangerous because a tiny amount can be a very large dose.
How much caffeine is in an energy drink?
An 8-ounce energy drink has about 72 mg of caffeine, so a 16-ounce can is about 144 mg. A 2-ounce energy shot has about 215 mg, more than half the adult daily limit in one go. Check the label, since brands vary widely.
Sources and further reading
This calculator is for general information only and is not medical advice. If you're pregnant, have a health condition or take medication, ask your doctor what's right for you.