From a single espresso to a mug of instant: the caffeine numbers behind every cup, the daily amounts EFSA and the NHS consider sensible, and the right time for your last coffee.
Key Takeaways
A typical cup of coffee contains 60 to 200 mg of caffeine, depending on the bean, the brew method, the serving size and the dose.
A single espresso holds around 60 to 80 mg, a mug of filter coffee 95 to 140 mg, and a cup of instant 60 to 100 mg.
For healthy adults, EFSA sees no safety concerns at up to 400 mg of caffeine a day and up to 200 mg in a single sitting; the NHS advises a 200 mg daily limit in pregnancy.
Caffeine's half-life averages around four hours, and caffeine even six hours before bed has been shown to disrupt sleep, so keep it to the first half of your day.
Jitteriness, a racing heart, an unsettled stomach and lighter sleep are the main signs you have gone past the dose that suits you.
Evan Lynch is a CORU-registered dietitian with a BSc in Food Science and Health, a Postgraduate Diploma in Dietetics, and an MSc in Sports Nutrition. Evan is the Head of Nutrition for Europe at AG1, where he supports strategic nutrition direction, education, and evidence-based communication. Alongside this role, he runs a private practice supporting clients across sports nutrition, gastrointestinal disorders, geriatric nutrition, and weight management.
A typical cup of coffee contains somewhere between 60 and 200 mg of caffeine. The range is wide because four things pull the number around:
This is why the numbers online never quite agree. Taste, by the way, is a poor guide: a bitter, intense espresso often contains less caffeine than an innocent-looking mug of filter.
The table below gives typical caffeine values per serving, based on USDA food-composition data and published figures from the NHS, the FDA and EFSA. Real cups vary, so read them as good averages.
Two things stand out. First, instant coffee sits meaningfully lower than filter, so a "cup of coffee" at home and a "cup of coffee" from a café are not the same dose. Second, caffeine adds up from places people forget to count: tea, cola, chocolate, and workout products. commonly contain 150 to 400 mg per serving, which is anywhere from one to several coffees in a single scoop.
The clearest benchmark comes from EFSA, which reviewed the evidence in 2015 and concluded that for healthy adults, up to 400 mg of caffeine per day, and up to 200 mg in any single sitting, raises no safety concerns.⊕
Translated into actual drinks, 400 mg looks like roughly:
The 200 mg single-serving figure matters too, and it is the one people miss. The pattern of your intake counts, not just the total: three coffees spaced through the morning sit within the guidance, while a triple-shot drink in one go can nudge past the single-sitting mark on its own.
These are benchmarks, not targets. Plenty of people feel best well under 400 mg, and there is no reason to drink up to a limit. But if you are a two-or-three-cup person wondering whether to worry, the evidence says you are fine. If anything, the research leans your way: a large umbrella review in the BMJ, pooling more than 200 meta-analyses, found coffee drinking associated with more benefit than harm overall, with the largest associations at around three to four cups a day. Those are observational findings rather than proof of cause and effect, but they are reassuring ones.
For some people the sensible ceiling sits lower:
Caffeine has a half-life of around four hours in healthy adults, with a range of roughly two to eight hours.⊕ Half-life means the time your body takes to clear half of a dose, so the maths is more persistent than most people assume: at the average clearance rate, half of a 3pm coffee's caffeine is still circulating at 7pm, and a quarter of it near 11pm. Slow metabolisers hold on to it for far longer.
A study by Drake and colleagues, published in the Journal of Clinical Sleep Medicine in 2013, gave participants 400 mg of caffeine at bedtime, three hours before bed and six hours before bed.⊕ Even the six-hour dose measurably disrupted sleep, cutting objectively recorded sleep time by more than an hour, and participants underestimated the effect in their own sleep diaries. In other words, caffeine can cost you sleep without you ever feeling that it did.
The practical rule that falls out of this is simple: keep caffeine to the first half of your day. If you are usually in bed at 11pm, treat early-to-mid afternoon as last orders, and earlier still if you know you are a slow metaboliser. You do not need to track anything; you just need a personal cut-off you actually keep.
Because the comfortable dose varies so much from person to person, your own signals are the best gauge of your sweet spot. The common signs of overshooting it are:⊕
Common caffeine side effects such as restlessness and disturbed sleep usually trace back to dose and timing. If that list describes your average Tuesday, the fix is rarely dramatic. Dropping one cup, halving the last one of the day, or moving your cut-off an hour earlier is usually enough to find the level where coffee works for you rather than on you. Worth remembering what caffeine actually does, too: it borrows alertness rather than creating energy, so it works best on top of decent sleep and regular meals, not instead of them.
Not for most healthy adults. It is the amount EFSA considers unproblematic in a single sitting, and half its 400 mg daily benchmark. In drink terms it is roughly two mugs of instant coffee or one large double-shot coffee. It is, however, the full daily limit the NHS advises during pregnancy.
A little. Decaffeination removes most but not all caffeine, leaving roughly 2 to 15 mg per cup against 60 to 140 mg in a regular coffee.⊕ For almost everyone, including people cutting down for sleep, that trace amount is negligible, which makes decaf a useful evening option.
Cup for cup, no. Black tea carries around 40 to 50 mg per cup and green tea around 25 to 30 mg, against 60 to 140 mg for coffee, so even a strong builder's brew sits well below an average mug of filter.
With an average half-life of about four hours, a dose of caffeine takes the better part of a day to clear almost completely, though the noticeable effects fade much sooner. Slow metabolisers clear it more slowly, which is why the same afternoon coffee bothers one person's sleep and not another's.
A cup of coffee contains anywhere from 60 to 200 mg of caffeine depending on how it is made, with instant at the lower end and large double-shot drinks at the top. For healthy adults, EFSA's benchmark of up to 400 mg a day and 200 mg in one sitting is a generous ceiling that comfortably fits a normal coffee habit, with a lower 200 mg daily figure from the NHS in pregnancy. The number that improves most people's sleep is not the limit but the clock: with a half-life of around four hours, and up to eight for slow metabolisers, coffee kept to the first half of the day gives you the alertness without the 1am ceiling-staring. Know your numbers, notice your own signals, and enjoy the rest.
For quick reference: a single espresso is around 60 to 80 mg,⊕⊕ a mug of filter coffee roughly 95 to 140 mg,⊕ and a cup of instant around 60 to 100 mg, with the NHS using 100 mg as its working figure.⊕
One more reason the numbers wander: the same drink varies from café to café. When researchers analysed 20 espressos bought from high-street coffee shops, caffeine content varied six-fold between outlets, and the strongest single espresso carried 322 mg, more than some people drink in a whole day.⊕ A coffee, in other words, is not just a coffee, so read the figures that follow as typical values rather than guarantees.
On blood pressure, since it is a common worry: caffeine can raise blood pressure modestly for a short period after drinking it,⊕ and regular drinkers develop a partial tolerance to this effect.⊕ For most healthy people it is not a reason to give up coffee, but it is a fair reason for anyone managing hypertension to talk timing and quantity through with their GP. Caffeine is simply a dose-dependent stimulant, and different people do best on different doses.
