By Luke Dalton. Updated 10 June 2026.

In 30 seconds. A standard 237ml (8 fl oz) cup of filter coffee contains about 96mg of caffeine. A single espresso carries around 63mg, a cup of instant about 62mg, and decaf just 1 to 2mg. The bean matters more than the roast: robusta naturally holds roughly twice the caffeine of arabica, which is how Contact Coffee Co's Red On, a speciality robusta, was voted one of the world's strongest coffees at 1,293mg per 12 fl oz (355ml) brewed serving. For healthy adults, the European Food Safety Authority considers up to 400mg a day, and 200mg in a single sitting, of no safety concern.

Want the strong end of the scale? Red On high-caffeine coffee is the flagship: speciality robusta, voted one of the world's strongest coffees. Prefer it ready to drink? The canned Americano carries 200mg per 250ml can with no sugar.

How much caffeine is in a cup of coffee?

The honest answer is that it depends, but the dependable baseline comes from the Mayo Clinic's caffeine tables: a standard 237ml (8 fl oz) cup of brewed filter coffee contains about 96mg of caffeine. That 237ml measure is smaller than most British mugs, which usually hold 250ml to 350ml, so a normal mug of filter coffee at home tends to land between 100mg and 140mg.

Four things move that number. The first is the bean: robusta carries roughly twice the caffeine of arabica, so a robusta-based coffee starts ahead before you have even brewed it. The second is the dose, simply how much coffee goes into the water, which is why a strong home brew can out-caffeinate a weak cafe one. The third is the brew method and contact time, since longer extraction pulls out more caffeine. The fourth is serving size, the quiet one that catches people out: a large 400ml takeaway cup is nearly two standard cups in one.

One thing that barely moves the number is the roast. Dark roasts taste stronger, but roasting changes flavour far more than it changes caffeine. If you want more caffeine in the cup, change the bean or the dose, not the roast colour. We unpack that fully in our guide to what coffee strength actually means.

Method by method, the pattern is consistent. Espresso is the most concentrated per millilitre but the smallest serving. Filter and pour over sit at the standard, around 96mg per cup. A cafetière lands in the same territory, often slightly higher because the grounds steep in the water for several minutes. Cold brew is the wildcard: the long steep pulls plenty of caffeine into the concentrate, so a glass of neat cold brew can be one of the stronger drinks in this list, though most people dilute it. If you make your own, our guide to making cold brew coffee covers ratios properly.

Caffeine by drink: the quick reference

The figures below use the Mayo Clinic's standard serving data for the everyday drinks, with the Contact Coffee Co figures taken from our own product pages. Treat them as reliable averages rather than absolutes, because every brew varies.

Two things stand out. A standard energy drink actually carries less caffeine than a mug of filter coffee, despite the branding. And purpose-built high-caffeine coffee operates in a different league entirely: Red On brews at around nine times the concentration of a typical filter coffee, which is exactly why it exists for the moments that need it.

Coffee vs tea vs energy drinks

Coffee is comfortably the strongest of the everyday drinks. A 237ml cup of black tea carries about 48mg of caffeine, half the filter coffee figure, and green tea sits lower still. Tea also delivers its caffeine alongside l-theanine, an amino acid that takes the edge off the spike, which is why a cup of tea feels gentler than the numbers alone suggest.

Energy drinks are the surprise. For all the aggressive branding, a standard energy drink carries about 79mg per 237ml, less than a mug of filter coffee, and it usually arrives with a serious payload of sugar. A black coffee, or a no-sugar canned Americano, delivers more caffeine with none of it. The genuinely high numbers in the energy aisle come from concentrated energy shots, which is a different product doing a different job.

The practical takeaway: if you are choosing a drink for the caffeine, coffee gives you the most control. You can run the whole scale, from a 1mg decaf to a 96mg filter cup to a purpose-built robusta, and know roughly what you are getting at each step.

What caffeine actually does, and why timing matters

Caffeine works by getting in the way of adenosine, the chemical that builds up through the day and makes you feel sleepy. With the sleepy signal blocked, you feel more alert, reactions sharpen and effort feels easier, which is exactly why coffee before training works and why we built a coffee strong enough to be a genuine pre-workout.

It moves fast and lingers long. Caffeine is absorbed quickly, typically peaking within about an hour of drinking, and the average half-life is around five hours. That means half of a 200mg afternoon coffee is still circulating five hours later, quietly blocking the sleepy signal when you would rather it did not. This is the single most useful fact in this whole guide: the caffeine that ruins sleep is usually not the morning cup but the late one.

Tolerance is real too. Regular drinkers feel less of a kick from the same dose, which tempts people to escalate. The smarter play is to keep your everyday coffee moderate and save the heavy hitters for the moments that genuinely need them, so the strong stuff still lands when you reach for it.

How much caffeine is in instant coffee?

Instant is the UK's everyday coffee, and it sits at the lighter end of the scale: about 62mg of caffeine in a 237ml cup, roughly a third less than the same cup of filter. The granules have already been brewed and dried, and the standard one-cup dose simply carries less caffeine than fresh grounds brewed properly.

The teaspoon question has a simple answer. One rounded teaspoon of instant is the standard dose for one cup, so a teaspoon carries roughly 60mg of caffeine. Make it two teaspoons and you are at around 120mg, which is how plenty of people quietly brew their instant stronger than a filter coffee without realising it.

If you like the convenience of instant but want proper coffee and a proper hit, single-serve brew bags are the upgrade: real ground coffee that brews like a teabag. Our Red On coffee bags give you the strongest coffee in the range with the same zero-kit convenience as a jar of granules.

How much caffeine is in decaf coffee?

Decaf is not caffeine-free, but it is close. A 237ml cup of brewed decaf carries about 1mg of caffeine, and instant decaf about 2mg, against 96mg for regular filter. The decaffeination process strips out nearly all of the caffeine before roasting, leaving the flavour and the ritual with almost none of the stimulant.

That makes decaf the right tool for two jobs: the evening cup that will not cost you sleep, and keeping your total intake down on days when you have already had your fill. If you are cutting back rather than cutting out, swapping your afternoon cup for decaf is the easiest single change you can make. Our decaffeinated coffee is the same speciality standard as the rest of the range, just with the off-switch built in.

Which coffee has the most caffeine?

Strip away the marketing and three factors decide it. The bean species comes first: robusta naturally contains roughly double the caffeine of arabica, which is why almost every genuinely strong coffee in the world is built on robusta. We cover the science properly in our robusta vs arabica guide. Second is the dose, how much coffee meets how much water. Third is the method: espresso is the most concentrated per millilitre, but a big mug of filter usually delivers more total caffeine than a single shot.

At the top of the scale sit the purpose-built high-caffeine coffees. Red On is Contact Coffee Co's flagship: a speciality Indian robusta, roasted in the UK, voted one of the world's strongest coffees, brewing at 1,293mg of caffeine per 12 fl oz (355ml) serving. It is black coffee built for the moments that need real fuel, an early start, a hard session, a long drive, rather than an everyday sipper.

For the full rundown of the strongest options available in Britain, our guides to the strongest coffee in the UK and which coffee has the most caffeine rank the field properly.

Caffeine in Contact Coffee products

We publish our figures, because if you are choosing coffee for the caffeine you deserve real numbers rather than vague promises. Here is how the Contact Coffee Co range maps onto the scale.

At the top is Red On ground coffee, the speciality robusta voted one of the world's strongest coffees at 1,293mg per 12 fl oz brewed. The same coffee comes as single-serve Red On coffee bags for strength without the kit.

In the canned range, the Americano carries 200mg of caffeine per 250ml can, black with no sugar, which makes one can exactly the EFSA single-dose guide level. The Latte is the smoother option at 150mg per can, and the Red On Americano can is the strongest of the three, with its figure on the label. The brand by brand comparison lives in our guide to how much caffeine is in a can of coffee, and the range story in our canned coffee guide.

Off the coffee scale entirely, Red On caffeine pouches deliver caffeine without brewing anything, covered in our caffeine pouches guide, and the decaf holds the other end of the line at next to nothing.

How much caffeine is safe in a day?

The clearest guidance for the UK comes from the European Food Safety Authority, whose 2015 scientific opinion concluded that for healthy adults, up to 400mg of caffeine a day from all sources, and single doses of up to 200mg, do not raise safety concerns. In coffee terms, 400mg is roughly four cups of filter, six cups of instant, or two cans of our Americano.

Pregnancy is the big exception. The NHS advises no more than 200mg a day during pregnancy, because regularly exceeding that level is linked to complications such as low birthweight. That total includes tea, chocolate, energy drinks and some medicines, not just coffee.

Timing matters as much as totals. Caffeine peaks within about an hour and has an average half-life of around five hours, so half of a 3pm coffee is still working at 8pm. If sleep is precious, set your cut-off six to eight hours before bed and let decaf carry the evening. And the boring truth that still beats every chart: if caffeine leaves you jittery, anxious or sleepless, that is your number telling you it is too high, whatever the guideline says.

Frequently asked questions about caffeine in coffee

How much caffeine is in a cup of coffee?

A standard 237ml (8 fl oz) cup of filter coffee contains about 96mg of caffeine, according to Mayo Clinic figures. Most UK mugs are bigger than that, around 250ml to 350ml, so a typical mug of filter coffee at home usually lands somewhere between 100mg and 140mg. The exact figure depends on the bean, how much coffee is used, and how it is brewed.

How much caffeine is in instant coffee?

A 237ml cup of instant coffee contains about 62mg of caffeine on average, which is roughly a third less than the same cup of filter coffee. The strength of the granules and how heaped your spoonful is both move that number, but as a rule instant sits at the lighter end of the coffee scale.

How much caffeine is in a teaspoon of instant coffee?

One rounded teaspoon of instant coffee is the standard dose for one cup, so it carries roughly 60mg of caffeine. Use two teaspoons and you roughly double it to around 120mg. The exact figure varies by brand and by how generous the spoonful is, but the one spoon, one cup, about 60mg rule is a reliable guide.

How much caffeine is in an espresso shot?

A single 30ml shot of espresso contains about 63mg of caffeine. A double shot, which is the standard base for most UK flat whites, lattes and americanos, is therefore around 126mg. Espresso is the most concentrated form of coffee, but because the serving is small, a full mug of filter coffee usually delivers more total caffeine.

How much caffeine is in decaf coffee?

Very little, but not none. A 237ml cup of brewed decaf contains about 1mg of caffeine and instant decaf about 2mg, compared with 96mg in regular filter coffee. The decaffeination process removes nearly all of the caffeine, so decaf is a sensible choice in the evening or if you are keeping your intake very low.

Which coffee has the most caffeine?

Coffee made from robusta beans, brewed strong. Robusta naturally carries roughly twice the caffeine of arabica, which is why the strongest coffees in the world are built on it. Contact Coffee Co's Red On is a speciality robusta voted one of the world's strongest coffees, brewing at 1,293mg of caffeine per 12 fl oz (355ml) serving.

Is 200mg of caffeine a lot?

It is a solid hit but within sensible limits for most people. The European Food Safety Authority considers single doses of up to 200mg of no safety concern for healthy adults. In practical terms, 200mg is about two cups of filter coffee, three cups of instant, or exactly one 250ml can of Contact Coffee Co's Americano.

How much caffeine is safe per day?

For healthy adults, the European Food Safety Authority considers up to 400mg of caffeine a day, from all sources, to be of no safety concern. That is roughly four cups of filter coffee. The NHS advises no more than 200mg a day during pregnancy. Caffeine in tea, energy drinks, chocolate and some medicines all counts towards the total.

How long does caffeine last?

Caffeine is absorbed quickly, typically peaking within about an hour, and it hangs around: the average half-life is roughly five hours, meaning half the dose is still in your system five hours later. That is why a strong coffee late in the afternoon can disturb sleep, and why many people set a cut-off six to eight hours before bed.

Does a latte have less caffeine than an americano?

Not if they are made with the same espresso shots, because milk does not remove caffeine, it only dilutes the taste. In ready-to-drink cans the recipes do differ: Contact Coffee Co's canned Americano carries 200mg of caffeine per 250ml can, while the canned Latte carries 150mg, so the black option is the stronger of the two.

Does dark roast coffee have more caffeine?

No, this is one of the most common coffee myths. Roasting changes flavour far more than it changes caffeine, and the difference between a light and dark roast of the same bean is small. What actually decides the caffeine in your cup is the bean species, robusta or arabica, how much coffee is used, and how it is brewed.

How much caffeine is in a can of coffee?

It varies by brand and recipe, so check the can. Within the Contact Coffee Co canned range, the Americano carries 200mg of caffeine per 250ml can and the Latte carries 150mg, with both figures printed on the product pages. Red On Americano is the strongest can in the range, with its caffeine content shown on the label.

Know your number, then pick your tool: Red On for maximum strength, the 200mg canned Americano for measured fuel on the move, and decaf for the evenings.

Related guides

Go deeper into the strong end of the scale with our guides to the strongest coffee in the UK, which coffee has the most caffeine and the robusta vs arabica caffeine difference. For what "strong" actually means on a bag, read the coffee strength scale explained. And if you want your caffeine cold and ready to drink, start with the best canned coffee in the UK, then compare every brand's numbers in how much caffeine is in a can of coffee.

References and further reading

Standard caffeine figures for brewed, instant, espresso and decaf coffee, tea and energy drinks: Caffeine content for coffee, tea, soda and more, Mayo Clinic. Safe-intake guidance for healthy adults: Scientific Opinion on the safety of caffeine, European Food Safety Authority (2015). Caffeine guidance in pregnancy: Foods to avoid in pregnancy, NHS.