Green tea does contain caffeine, but typically less than black tea. An 8-ounce cup of green tea delivers roughly 23 to 49 milligrams of caffeine, while black tea ranges from about 30 to 100 milligrams depending on the variety. The gap between them is real but not enormous, and how you brew your tea can matter just as much as which type you choose.
Caffeine by the Numbers
Green tea averages around 29 milligrams of caffeine per 8-ounce cup, though the range stretches from 23 to 49 milligrams. Black tea covers a wider spectrum. A cup of Darjeeling can land anywhere from 26 to 44 milligrams, overlapping with green tea entirely. English Breakfast runs 30 to 60 milligrams. Assam, one of the strongest common black teas, hits 60 to 100 milligrams per cup.
For context, an 8-ounce cup of brewed coffee contains 75 to 195 milligrams of caffeine. So even the strongest black tea delivers roughly half to two-thirds the caffeine of a typical coffee, and green tea delivers a quarter to a third. If you’re looking to cut back on caffeine without eliminating it, either tea is a significant step down from coffee.
Why the Range Is So Wide
You’ll notice the caffeine numbers for both green and black tea aren’t single figures. That’s because caffeine content depends on several factors that have nothing to do with the color of the tea in your cup.
Leaf age and position on the plant are major drivers. Buds and young, tender leaves concentrate more caffeine than older, larger leaves. A tea like Lapsang Souchong, made from mature leaves, sits on the lower end of the black tea spectrum. Meanwhile, some white teas made primarily from buds can surprise people by testing higher than expected.
Leaf grade also plays a role. Many mass-market black teas use smaller, broken leaf particles (the kind inside tea bags) that release caffeine quickly into water. Whole-leaf green teas, which are more common in loose-leaf form, extract more slowly. This is one reason black tea “often ends up higher in the cup,” as tea researchers put it. It’s not just the leaf itself but how finely it’s been processed.
How Brewing Changes Everything
The instructions on your tea box aren’t just about flavor. Black tea is typically brewed at or near boiling (around 200 to 212°F) for 3 to 5 minutes. Green tea is usually brewed cooler (160 to 180°F) for 1 to 3 minutes. Both of those differences push more caffeine into your black tea cup.
Hotter water pulls more caffeine from leaves. Research published in the journal Foods found a general trend of increased caffeine extraction at higher temperatures across all tea types. In oolong tea specifically, caffeine levels more than tripled when brewing temperature jumped from 175°F to 212°F. Longer steep times compound the effect. So if you steep your green tea in boiling water for five minutes, you’ll extract noticeably more caffeine than the standard range suggests. Conversely, a short, gentle steep of black tea will yield less.
The practical takeaway: the “green tea has less caffeine” rule holds true under standard brewing conditions, but you can nudge the numbers in either direction by adjusting temperature and time.
Matcha Is a Different Story
If you drink matcha, the comparison shifts. Matcha is green tea, but because you’re consuming the whole powdered leaf rather than steeping and discarding it, you get significantly more of everything in the leaf, including caffeine. Harvard Health estimates matcha at 38 to 89 milligrams per 8-ounce serving, which puts it squarely in black tea territory or even above it.
So when people say “green tea is lower in caffeine,” that’s true for standard steeped green tea. Matcha is the major exception.
Why Green Tea Feels Different
Many people report that green tea gives them a calmer, more focused energy than black tea or coffee, even accounting for the lower caffeine dose. The reason is an amino acid called L-theanine, which promotes relaxation without drowsiness. Green tea contains the highest concentration of L-theanine among tea types, averaging 6.56 milligrams per gram of dry leaf. Black tea averages 5.13 milligrams per gram.
That difference matters because of how L-theanine interacts with caffeine. The two compounds have opposing effects on the brain: caffeine stimulates, L-theanine calms. Research shows that L-theanine partially counteracts caffeine’s jittery, anxious edge. But the two also work together synergistically to improve attention and focus, as demonstrated in brain-wave studies. The ratio between them is what determines how stimulating a cup of tea actually feels.
Green tea, with its higher L-theanine relative to its lower caffeine, has a more balanced ratio. Black tea’s ratio tilts more toward stimulation. Neither will hit you like coffee, but the subjective experience of alertness can feel noticeably different between the two.
How Many Cups You Can Drink
The FDA considers up to 400 milligrams of caffeine per day a safe amount for most healthy adults. At roughly 29 milligrams per cup, you could drink about 13 cups of average green tea before reaching that ceiling. With a moderate black tea like English Breakfast at around 45 milligrams, you’d reach it at about 9 cups. With a strong Assam at 80 to 100 milligrams, you’re looking at 4 to 5 cups.
For most tea drinkers, caffeine intake isn’t a practical concern. Even three or four cups a day of either green or black tea keeps you well within recommended limits. Where it starts to matter is if you’re combining tea with coffee, energy drinks, or caffeine-containing medications throughout the day.