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A typical 8 oz (240 ml) cup of brewed coffee has about 96 mg of caffeine, according to the Mayo Clinic, and the NHS puts a cup of instant at about 100 mg. The real amount varies with the beans, the brewing and above all the cup size. For healthy adults, 400 mg a day is the commonly cited upper limit, roughly three to four standard cups.
Key takeaways
- A standard 8 oz cup of brewed coffee has about 96 mg of caffeine (Mayo Clinic); a cup of instant about 100 mg (NHS).
- A 12 oz brewed coffee can range from 113 to 247 mg (FDA), so cup size changes the total most.
- Espresso drinks get their caffeine from shots; a double roughly doubles it.
- Healthy adults: up to 400 mg a day and 200 mg in one go are the commonly cited limits (FDA, EFSA).
- Pregnancy: the NHS advises no more than 200 mg a day.
This page is general education for healthy adults aged 18 and over. It is not medical advice. If you have a health condition, are pregnant or take medication, check with a doctor or pharmacist.
Caffeine in common drinks
Published figures differ between sources because coffee itself differs. These figures from health bodies and a major medical centre are a sensible starting point:
| Drink | Approximate caffeine | Source |
|---|---|---|
| Brewed coffee, 8 oz (240 ml) | About 96 mg | Mayo Clinic |
| Brewed coffee, 12 oz (355 ml) | 113 to 247 mg | FDA |
| Espresso, 1 oz single shot | About 63 mg | Mayo Clinic |
| Cup of instant coffee | About 100 mg | NHS |
| Decaf coffee, 8 oz | 2 to 15 mg | FDA |
| Black tea, 8 oz | About 48 mg | Mayo Clinic |
| Cup of tea | About 75 mg | NHS |
| Can of cola | About 40 mg | NHS |
| Energy drink, 250 ml | About 80 mg | NHS |
Sources: the Mayo Clinic's caffeine content guide, the FDA's consumer guide to caffeine and the NHS pregnancy food guidance. The NHS notes that filter coffee and coffee-shop coffee can contain more than instant. If a café publishes caffeine figures for its drinks, use those.
Why the same "cup" can differ so much
- Cup size. A "cup" in research is often 8 oz (about 240 ml). A large café coffee can be two or more times that.
- Number of espresso shots. Lattes, flat whites and cappuccinos get their caffeine from espresso, so a double shot roughly doubles it. Milk adds volume, not caffeine.
- Beans, grind and brewing. The Mayo Clinic notes that caffeine levels vary with factors such as growing conditions and brewing time. How much coffee you use per cup matters too.
- Decaf is not zero. The FDA puts decaf at 2 to 15 mg per 8 oz.
How much is too much?
The FDA says 400 mg a day is an amount not generally associated with negative effects for most healthy adults, roughly two to three 12-ounce cups of brewed coffee. The European Food Safety Authority (EFSA) reached a similar view: up to 400 mg a day, and single doses of up to 200 mg, do not raise safety concerns for healthy adults. EFSA also notes that 100 mg close to bedtime may affect sleep in some adults.
These limits are lower for some people. The NHS advises no more than 200 mg a day in pregnancy, and people with certain health conditions or who take some medicines may need less. People also vary in sensitivity: some feel jittery or sleep badly on far less. The FDA lists signs of too much, including a fast heart rate, palpitations, insomnia, anxiety, jitters, an upset stomach and headache.
How many cups is that?
| Your usual coffee | Estimated caffeine each | Cups to reach about 400 mg |
|---|---|---|
| Instant, standard cup | About 100 mg | About 4 |
| Brewed, 8 oz | About 96 mg | About 4 |
| Brewed, 12 oz | 113 to 247 mg | About 2 to 3 |
| Double-shot latte | About 126 mg (two 63 mg shots) | About 3 |
| Large café filter coffee | Can exceed 200 mg | 2 or fewer |
These are rough estimates from the averages above. Your own drinks may be stronger or weaker.
Worked example: counting a normal day
Example: say your day looks like this. The figures are estimates for illustration.
- 8am: a large 16 oz brewed coffee. At Mayo Clinic's 96 mg per 8 oz, that is roughly 190 mg, close to the 200 mg single-dose level.
- 11am: a double-shot latte, roughly 126 mg.
- 3pm: a can of cola, about 40 mg.
That adds up to about 356 mg, close to the 400 mg daily limit. The 3pm cola also matters for sleep: a 2023 meta-analysis (open-access copy) estimated a normal coffee should be taken at least 8.8 hours before bed.
Two small swaps change the picture. A regular 8 oz coffee at 8am (about 96 mg) and a caffeine-free drink at 3pm bring the day to about 222 mg, with nothing near the single-dose level and nothing late in the day.
How to find the caffeine in your own drinks
The averages above are a starting point. To get closer to your real number:
- Check the label or the café's published figures. Many coffee chains and energy drink brands list caffeine per serving.
- Measure your mug. Fill it with water and pour it into a measuring jug. A "cup" at home is often 300 ml or more, not 240 ml.
- Count shots, not drinks. For espresso-based drinks, ask how many shots go into your usual size.
- Write down a normal day, with times, for two or three days. Add it up and note your largest single serving.
- Compare against the two lines: 200 mg in one go and 400 mg across the day, or 200 mg a day if you are pregnant.
If your largest serving is near 200 mg, a smaller cup or a single shot is the easiest change. If your total is near 400 mg, drop the latest drink of the day first, because that one also matters most for sleep.
Getting more from the caffeine you already drink
How much you drink is only half of it; when you drink it matters too. Timing coffee around your sleep, avoiding big single doses and noticing your own tolerance all change how useful caffeine feels. Secrets to Using Caffeine to Win is our practical playbook on exactly that, written as education for healthy adults, not medical advice.
FAQ
How much caffeine is in a shot of espresso?
The Mayo Clinic puts a 1 oz single shot at about 63 mg. It varies with the beans and the café. A double shot is roughly twice that.
How many cups of coffee a day is safe?
For most healthy adults, about three to four standard 8 oz cups stays within the 400 mg guideline. Large café coffees count as more than one cup.
How much caffeine is in decaf coffee?
The FDA puts decaf at 2 to 15 mg per 8 oz. It is not completely caffeine-free, but it is far lower than regular coffee.
Is instant coffee weaker than filter coffee?
Often, yes. The NHS gives about 100 mg for a cup of instant and notes that filter and coffee-shop coffee can contain more.
How long does the caffeine from a cup of coffee last?
Caffeine stays in your body for several hours, and the FDA notes that people clear it at very different rates. That is why an afternoon coffee can still affect your sleep at night.
Related guides: why are caffeine powders dangerous?, does caffeine dehydrate you? and how much caffeine is in pre-workout?
This is general information, not medical advice.