Green tea is relatively low in caffeine. An 8-ounce cup of brewed green tea contains about 29 milligrams of caffeine, which is less than a third of what you’d get from the same size cup of coffee (96 mg) and roughly half the caffeine in black tea (48 mg). For most people, green tea delivers a mild lift without the intensity of coffee.
How Green Tea Compares to Other Drinks
To put 29 milligrams in perspective, the FDA considers up to 400 milligrams of caffeine per day safe for most healthy adults. You could drink roughly 13 cups of green tea before hitting that ceiling. With brewed coffee at 96 mg per cup, you’d reach the same limit in just over four cups.
Black tea sits in the middle at about 48 mg per 8-ounce cup. So if you’re switching from coffee to green tea specifically to cut back on caffeine, you’re reducing your intake by about 70% per cup. Switching from black tea to green tea cuts it by about 40%.
Not All Green Teas Have the Same Caffeine
The variety of green tea you choose makes a big difference. Standard sencha, the most common type, contains around 20 mg of caffeine per 100 grams of brewed tea. Genmaicha (green tea mixed with roasted rice) has even less, closer to 10 mg. These are the lightest options.
Gyokuro, a premium shade-grown Japanese tea, is the outlier. It packs roughly 160 mg per 100 grams of brewed tea, putting it closer to coffee territory. The shade-growing process forces the plant to produce more caffeine and other compounds in its leaves. Matcha falls somewhere around 30 mg per serving, though the exact amount depends on how much powder you use. Because you’re consuming the whole leaf rather than steeping and discarding it, matcha delivers more caffeine than a typical steeped green tea.
If you want green tea with minimal caffeine, look for hojicha (roasted green tea) or kukicha (twig tea). Hojicha brewed at moderate temperatures contains roughly 11 to 14 mg per serving, while kukicha ranges from about 19 to 27 mg depending on how hot and long you brew it.
How Brewing Changes the Caffeine
Your brewing method has a surprisingly large effect on how much caffeine ends up in your cup. Two variables matter most: water temperature and steeping time.
Research measuring caffeine extraction in tea found dramatic differences across temperatures. At room temperature (about 68°F), a one-minute steep extracted barely any caffeine, just 1.4 mg per cup. At boiling (212°F), that same one-minute steep yielded over 25 mg. After four minutes at boiling, the caffeine climbed to nearly 43 mg. The relationship isn’t linear either. Most of the caffeine comes out in the first two minutes, with diminishing returns after that.
Green tea is traditionally brewed at lower temperatures than black tea, typically around 160 to 180°F rather than a full boil. This naturally keeps caffeine extraction lower. If you’re trying to minimize your caffeine intake, use cooler water and steep for a shorter time. If you want a stronger kick, hotter water and a longer steep will pull more caffeine from the leaves.
Why Green Tea Caffeine Feels Different
Many people notice that green tea produces a calmer, steadier alertness compared to coffee, even when the caffeine amounts are similar. This isn’t imagined. Green tea contains an amino acid called L-theanine that modifies how caffeine affects the brain. Animal studies have shown that L-theanine directly inhibits the stimulatory effects of caffeine, reducing the jitteriness and sharp energy spikes that coffee often produces.
The result is what tea drinkers often describe as “alert but relaxed.” You get improved focus and wakefulness from the caffeine, but L-theanine smooths out the edges. This combination is unique to tea and is one reason people who are sensitive to coffee’s side effects sometimes tolerate green tea well, even though both contain caffeine.
What About Decaf Green Tea?
Decaffeinated green tea removes the vast majority of caffeine, often reducing it to less than 3% of the original amount. But the process comes with a trade-off. Research on commercial decaffeination found that removing caffeine also strips away a significant portion of the tea’s beneficial antioxidants. One study measured a loss of nearly 38% of the tea’s primary protective compound during decaffeination.
If your goal is to avoid caffeine entirely, decaf green tea works. But if you’re drinking green tea partly for its health benefits, you’re giving up a meaningful share of those compounds in the process. For many people, the naturally low caffeine in regular green tea is manageable enough that decaf isn’t necessary.