2 brewed coffees and 1 espresso
253 mg a day, within 400 mg. About 127 mg left after 5 hours and 63 mg after 10.
Caffeine calculator
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Caffeine amounts are typical values from the USDA and FDA; real cups vary by brand and brew. The safe daily figure is 400 mg for healthy adults and 200 mg in pregnancy. The chart assumes all of it is taken at once, with a half-life of 5 hours, which in real life ranges from about 2 to 10 hours.
Daily limit for
Caffeine a day
253 mg
Within the 400 mg daily limit, with 147 mg to spare.
- Share of limit
- 63%
- Left after 5 hours
- 127 mg
- Left after 10 hours
- 63 mg
0 h12 h24 h
Brewed coffee190 mg
Espresso63 mg
Keeping track of caffeine
Caffeine adds up quickly across a day: a coffee at breakfast, an espresso after lunch, a cola in the afternoon. This tool adds the typical amounts and compares the total with the safe daily limit.
Two cups of brewed coffee and one espresso come to about 253 mg. That is within the 400 mg adult limit, but above the 200 mg advised in pregnancy.
Caffeine also lingers. With a 5-hour half-life, about 127 mg of that 253 mg is still in your body 5 hours later, and about 63 mg after 10 hours. If you sleep badly, look at what you drink after lunch.
Labels vary, so check energy drinks and supplements, some of which hold over 200 mg in one serving. Children, people with heart conditions and anyone on certain medicines should aim much lower. Ask a doctor if unsure.
Sources
What this calculator does not account for
- Brand-to-brand differences in caffeine.
- Supplements and medicines that contain caffeine.
- Personal half-life, which ranges from about 2 to 10 hours.
How this is calculated
Formula: Total and what remains
total =Σ (cups × mg per cup); left after t hours =total × 0.5^(t ÷ 5)What the symbols mean
- mg per cupTypical caffeine in each drink.
- 5Average caffeine half-life in hours for a healthy adult.
Good to know
- Half-life is longer in pregnancy and with some medicines, and shorter in smokers.
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Worked examples
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<iframe src="/embed/caffeine-calculator" title="Caffeine calculator" width="100%" height="720" style="border:0;max-width:42rem" loading="lazy"></iframe>Questions
How much caffeine is too much in a day?
For healthy adults the FDA and EFSA say up to 400 mg a day is generally safe. That is about four cups of brewed coffee.
How much caffeine is in a cup of coffee?
About 95 mg in a 240 ml cup of brewed coffee and about 63 mg in a single espresso, but it varies a lot by bean and brew.
How much caffeine is safe in pregnancy?
Up to 200 mg a day, according to the NHS and ACOG.
How long does caffeine stay in your system?
Half of it is gone in about 5 hours on average. 253 mg at 8 am leaves about 63 mg at 6 pm, which can still affect sleep.
Does tea have less caffeine than coffee?
Yes. Black tea has about 47 mg a cup and green tea about 28 mg.