Three cups before lunch, a cola at four and an energy drink on the drive home. Is that a normal Tuesday, or a problem?
The honest answer is that it depends on you. Health bodies give different limits for different people, and the drinks vary a lot in strength. This coffee calculator adds up the caffeine you have had today and compares it with a sensible daily limit for your situation, so you can see how many more cups you have room for.
How to use the Coffee Calculator#
- Choose who the limit is for. Pick healthy adult, breastfeeding, pregnant or teen.
- Say how you handle caffeine. Choose sensitive if a little keeps you wired or anxious.
- Enter your drinks. Add the number of coffees, espressos, teas, colas and energy drinks you have had.
- Read the result. You get your total in milligrams, your limit and the room you have left.
The daily limits behind the calculator#
These figures come from well-known health guidance:
| Group | Daily limit | Source of the guidance |
|---|---|---|
| Healthy adults | 400 mg | US Food and Drug Administration, and the European Food Safety Authority |
| Breastfeeding | 300 mg | Commonly advised for the nursing period |
| Pregnancy | 200 mg | American College of Obstetricians and Gynecologists |
| Ages 12 to 18 | 100 mg | American Academy of Child and Adolescent Psychiatry |
The European regulator also notes that single doses up to about 200 mg aren’t a concern for healthy adults, and that 100 mg close to bedtime can shorten sleep in some people.
How much caffeine is in a drink?#
The calculator uses typical amounts. Your own cup can differ by a lot, because roast, bean, brewing method and size all matter:
| Drink | Typical caffeine |
|---|---|
| Brewed coffee, 8 oz (240 mL) | 95 mg |
| Espresso, single shot | 63 mg |
| Black tea, 8 oz | 47 mg |
| Cola, 12 oz can | 34 mg |
| Energy drink, 8.4 oz | 80 mg |
A large takeaway coffee is often 16 to 20 oz, so it can count as two cups on its own. Count it that way.
A worked example#
You’re a healthy adult with a limit of 400 mg. You have had two cups of brewed coffee today, which is 2 × 95 = 190 mg. That’s 48 percent of your limit and it leaves 210 mg, enough for two more cups of coffee with a little to spare.
Now switch to “I am sensitive” and the limit halves to 200 mg. The same two cups put you at 95 percent of it, with just 10 mg left, so that’s your day.
About the “sensitive” setting#
People break down caffeine at different speeds, and the time it takes to clear half of a dose varies from roughly 2 to 8 hours between individuals. Genetics, medication and pregnancy all play a part. There’s no official sensitivity figure, so the calculator uses a cautious halving as a rule of thumb. If a small amount of caffeine gives you a racing heart, shakes or a bad night, trust your body over any number.
When to talk to a doctor#
This tool is for general information, not medical advice. Check with a doctor or pharmacist if you’re pregnant, have heart rhythm problems, anxiety, high blood pressure or reflux, or take medicines that interact with caffeine. Also remember hidden sources, such as pre-workout powders, some painkillers, chocolate and decaf coffee, which still holds a little.
A worked day#
Someone has two brewed coffees (95 mg each) and a can of cola (34 mg). That is 224 mg of caffeine. Against the adult limit of 400 mg, they have used 56 percent and have 176 mg left, enough for 1 more brewed coffee. If they add an energy drink at 80 mg, the day reaches 304 mg, still under the limit but with little room.
| Drink | Typical caffeine |
|---|---|
| Brewed coffee, 1 cup | 95 mg |
| Espresso shot | 63 mg |
| Black tea, 1 cup | 47 mg |
| Cola, 1 can | 34 mg |
| Energy drink, 1 can | 80 mg |
Real drinks vary a lot. A large coffee-shop cup can have 200 mg or more, and some energy drinks have double the amount used here, so check the label when you can.
Timing and sleep#
Caffeine stays in the body longer than most people expect. The half-life is about 5 hours in a healthy adult, though it ranges from 3 to 7. If you drink a coffee at 4 pm, about half the caffeine is still in your blood at 9 pm, which can delay sleep or make it less deep. Many people sleep better if they stop caffeine 8 hours before bed. Pregnancy, some medicines, liver conditions and oral contraceptives slow the clearing of caffeine, so the limit for these groups is lower, and the calculator’s group options reflect that. Cutting down too fast can cause headaches, so reduce gradually.
Frequently asked questions#
For most healthy adults, up to 400 mg of caffeine a day, which is about four 8 oz cups of brewed coffee. The limit is lower in pregnancy and for teens.
The American College of Obstetricians and Gynecologists advises staying under 200 mg a day, roughly two cups of brewed coffee.
About 95 mg in a typical 8 oz cup, but it can range from around 70 to 150 mg depending on the coffee and how it’s brewed.
Yes, a small amount, usually a few milligrams per cup. This calculator doesn’t count it.
Caffeine can stay in your system for hours. Many people sleep better if they stop six to eight hours before bed, though it varies from person to person.
Health agencies suggest up to 400 mg a day for most healthy adults, which is about four cups of brewed coffee. The limit is 200 mg for pregnant women in most guidance, and lower for children and teenagers. Individual sensitivity differs, so cut back if you feel jittery, anxious or can’t sleep.