A 300 ml mug of filter coffee carries roughly 95 to 165 mg of caffeine. The same mug of black tea carries 40 to 75 mg, green tea 25 to 45 mg, white tea 15 to 30 mg. Tea leaves are more caffeinated than coffee beans (around 4 per cent versus 0.9 to 2.6 per cent by dry weight), but tea uses less leaf per cup and brews at cooler temperatures. Coffee delivers about double the caffeine of black tea and three to four times that of green tea.
Most comparison articles online stop there. This one keeps going, because the headline number changes once you account for the UK mug, the steep time and whether you actually want the caffeine in the first place.
The short answer (with the actual milligrams)
Standard UK reference values, scaled to a 300 ml mug where the source uses 8 oz or 200 ml.
| Drink | Caffeine (mg, 300 ml mug unless stated) | Source basis |
|---|---|---|
| Filter coffee | 140 | NHS |
| Cafetière | 95 to 165 | Healthline scaled |
| Instant coffee | 100 | NHS |
| Espresso, single (30 ml) | 40 to 75 | UK roaster average |
| Espresso, double (60 ml) | 80 to 126 | EFSA, UE Coffee |
| Black tea | 40 to 75 | NHS, Healthline |
| Green tea | 25 to 45 | Healthline, Breville |
| Matcha (typical 2 g serving) | 60 to 70 | The Tea Makers, Esquires |
| White tea | 15 to 30 (range 6 to 60) | Breville |
| Oolong | 37 to 55 | Industry consensus |
| Cold brew | 100 to 200 (per 350 ml takeaway) | US convention |
| Decaf coffee | 2 to 7 (up to 15) | UK and EU regulation |
| Decaf tea | 2 to 5 | UK retailer averages |
| Rooibos, chamomile, peppermint | 0 | Naturally caffeine free |
The NHS publishes per-mug figures in its pregnancy guidance without specifying a mug volume, but the numbers map closely to a standard UK mug rather than a US 8 oz cup. Healthline and Mayo use an 8 oz cup (237 ml). Scale up by 27 per cent if you want the 300 ml UK mug figure from a US source. That single adjustment is why most online caffeine numbers feel slightly off.
For a fuller drink by drink breakdown with brew method variations, see the milligrams of caffeine per cup guide.
Why tea leaves contain more caffeine than coffee beans (but tea still has less)
Gram for gram, tea leaves are roughly twice as caffeinated as coffee beans. Tea sits around 4 per cent caffeine by dry weight. Arabica coffee is 0.9 to 2.6 per cent.
What flips the result in the cup is dose, temperature and time.
A standard teabag is about 2 g of leaf. A filter coffee dose is closer to 10 g of ground beans, five times the raw material. Black tea is brewed at around 91°C and green tea at 79°C, while filter coffee runs at 90 to 96°C with much longer contact time. Hotter water extracts more efficiently, though within the typical tea brewing range the temperature effect on caffeine is smaller than commonly assumed.
A teabag is one fifth the mass of a coffee dose, brewed cooler, for shorter contact. Even though the leaf is twice as caffeinated by weight, the cup ends up at about a third the dose.
Caffeine by tea type
Black tea
Black tea (English Breakfast, Earl Grey, Assam) sits at 40 to 75 mg per 300 ml mug. The NHS publishes 75 mg per mug as its pregnancy reference. Healthline lands around 50 mg per 220 ml. For most readers drinking a normal supermarket teabag at a normal steep, expect 60 to 70 mg.
Green tea
A 300 ml mug of green tea carries 25 to 45 mg of caffeine. Half a black tea, a quarter of a filter coffee. Sencha and gunpowder land in the same range. The standard recommendation is 79°C for three minutes. Hotter water extracts more caffeine, but also more tannins, which makes the cup bitter.
Matcha
Matcha is its own category because you drink the leaf rather than an infusion. A 2 g serving whisked into 200 to 250 ml of water carries 60 to 70 mg of caffeine. By the gram, matcha is more caffeinated than coffee beans (around 32 mg per gram versus 10 to 12 mg per gram for arabica). By the cup, a typical matcha sits above standard green tea but well below brewed coffee.
If you have read that matcha is higher in caffeine than coffee, the answer depends on the unit. By gram, yes. By cup, no.
White tea
White tea has the widest published range of any tea: 6 to 60 mg per 8 oz cup. The buds are higher in caffeine than mature leaves, so a young Silver Needle can rival a green tea while an older bai mu dan comes in close to herbal. Take 15 to 30 mg per mug as the typical figure, with a wider error bar than other categories.
Oolong
Oolong sits between green and black, in oxidation and in caffeine: 37 to 55 mg per 300 ml mug. Lighter oolongs lean towards green tea numbers, darker oolongs lean towards black.
Herbal teas
Rooibos, chamomile, peppermint, hibiscus, fennel, ginger and lemon balm are naturally caffeine free. They are not Camellia sinensis, just plants infused in hot water. Zero milligrams.
Two exceptions. Yerba mate carries around 80 mg per cup, similar to filter coffee. Guayusa is comparable. Some energy herbal blends use guarana, which is heavily caffeinated. Read the label rather than assuming all herbals are zero.
Caffeine by coffee type
Espresso
A single 30 ml shot carries 40 to 75 mg of caffeine. A double 60 ml shot carries 80 to 126 mg. The drink tastes stronger than tea because of the concentration, but total caffeine per serving sits in the same range as a mug of filter, sometimes lower. A UK flat white or cappuccino is a double shot in 150 to 250 ml of milk, so caffeine is closer to 130 mg.
Filter, cafetière, pour over
Filter coffee in a 300 ml UK mug carries about 140 mg of caffeine according to NHS pregnancy guidance. EFSA’s per litre figure works out around 135 mg per mug. Healthline’s wider 90 to 200 mg per 8 oz scales to 95 to 165 mg.
If you want a single number to remember, 140 mg per mug is the UK working figure.
Instant coffee
Instant coffee carries 100 mg per 300 ml mug. Lower than filter because freeze dried granules extract less efficiently than fresh ground beans. Convenience for about 30 per cent less caffeine.
Cold brew
No UK primary source publishes a settled figure. US convention is 100 to 200 mg per 12 oz (350 ml) serving, with undiluted concentrate going considerably higher. Treat any single number as approximate. Cold brew varies more than any other method because the dilution ratio is set by the seller.
Decaf coffee, which still contains some
UK and EU regulations require decaf coffee to be at least 99.9 per cent caffeine free by dry weight on the bean. In a brewed cup, that works out at 2 to 7 mg of caffeine, with outliers up to 15 mg. A US study (McCusker et al., Journal of Analytical Toxicology, 2006) measured 0 to 13.9 mg per 16 oz serving across ten high street coffee shop decafs. For the full picture, see does decaf coffee contain caffeine and residual caffeine in decaf.
What changes the caffeine in your cup
The brew variables that move the number, in order of how much they matter.
Water temperature. Hotter water extracts more efficiently in principle, but within the typical 79 to 100°C tea brewing range the effect on caffeine yield is smaller than often claimed. The bigger reason to respect the recommended 79°C for green tea is taste, not caffeine: the same leaves dunked in 100°C water come out harsh and tannic.
Steep time. A familiar curve, worth showing in actual numbers. For a standard English Breakfast teabag:
| Steep time | Approx caffeine (mg) |
|---|---|
| 1 minute | 14 |
| 3 minutes | 35 to 45 |
| 5 minutes | 50 to 65 |
After about two minutes, extraction starts to plateau. You keep pulling tannins and bitterness past that point, but the caffeine yield slows. Most of the load is out by the end of minute two. If you want a milder brew, take the bag out earlier rather than diluting with water.
Grind size and leaf cut. Smaller particles mean more surface area, which means faster extraction. A CTC teabag, with the leaf cut fine, extracts faster than a whole leaf. Espresso grind extracts faster than filter grind. For tea, a finer cut means a stronger cup at the same time and temperature.
Roast level. A persistent myth. By weight, lighter roast has marginally more caffeine because roasting burns off bean mass faster than caffeine. By volume (scoop), darker roast has marginally more for the same reason. By cup with a standard dose, the difference is under 10 per cent. Treat dark and light roast as broadly equal on caffeine.
Cup size. The biggest gap between published numbers and reality. A US cup is 8 oz (237 ml). A typical UK home mug is 250 to 330 ml. A 300 ml mug delivers 27 per cent more caffeine than an 8 oz cup at the same brew strength. A high street takeaway small (12 oz, 355 ml) is 50 per cent over the published 8 oz figure.
Does caffeine from tea feel different to caffeine from coffee?
Some.
The molecule is identical. C8H10N4O2 either way. The difference is what arrives with it.
Tea contains L-theanine, an amino acid that crosses the blood brain barrier and stimulates alpha brain wave activity associated with relaxed concentration. Coffee contains essentially none. A 2008 study in the Journal of Nutrition (Kelly et al.) found that 100 mg of L-theanine combined with 50 mg of caffeine produced sharper attentional task performance than either on its own. A 2021 systematic review in Cureus (Sohail et al.) reached similar conclusions.
Tea’s tannins also bind to caffeine in the gut and slow absorption. Caffeine from tea peaks later (around 60 minutes) and lower than caffeine from coffee (30 to 45 minutes). A coffee hit arrives sharper. A tea hit climbs and holds.
Honest framing. A typical UK mug of black tea delivers about 25 mg of L-theanine alongside 60 mg of caffeine. The studies that show clear cognitive effects use four times that theanine dose. The effect at one mug is real but modest. Do not expect a green tea to feel like a different drug. Expect it to feel like the same drug delivered more smoothly.
How much caffeine is too much (UK guidance)
The NHS and the European Food Safety Authority both put the safe daily caffeine limit at 400 mg for healthy adults. EFSA’s exact wording is that “intakes up to 400 mg per day consumed throughout the day do not raise safety concerns for healthy adults”.
For pregnant women, both halve it: 200 mg per day.
In UK mug terms:
- 400 mg is about three mugs of filter coffee, four mugs of instant, or five mugs of black tea
- 200 mg is about one and a half mugs of filter, two mugs of instant, or two and a half mugs of black tea
Tea is the UK’s dominant caffeine source. EFSA survey data puts it at 57 per cent of total caffeine intake, unlike the US where coffee dominates. If you are over the limit and want to cut back, tea is where most of the volume sits.
If caffeine is why you’re reading this
A reasonable chunk of the traffic on this page lands here because someone is trying to work out whether they can keep coffee in their life. The short version: yes.
UK and EU regulation requires decaf coffee to remove at least 99.9 per cent of the caffeine from the bean, leaving 2 to 7 mg per cup against 140 mg in a regular mug. Decaffeinate.co.uk runs a directory of UK specialty decaf coffees, organised by decaffeination method. Swiss Water, supercritical CO2 and ethyl acetate (sugar cane) are the three specialty grade processes. None of them taste like the supermarket instant decaf you remember from a relative’s kitchen.
These are more useful doors than another caffeine table.
- The full list of UK specialty decaf coffees
- How to switch to decaf without losing the ritual
- Decaf versus regular coffee side by side
The decision is rarely between caffeine and no caffeine. It is more often between caffeine you can keep enjoying and caffeine that has stopped working for you. Most of the people who read this site have already worked out which one they are.