An 8-ounce cup of brewed green tea contains about 29 mg of caffeine, while the same size cup of brewed coffee contains about 96 mg. That means coffee delivers roughly three times as much caffeine per cup. But those numbers shift considerably depending on the type of tea or coffee you choose and how you prepare it.
The Basic Numbers Side by Side
For a standard 8-ounce serving, here’s what you’re looking at:
- Brewed green tea: ~29 mg of caffeine
- Brewed drip coffee: ~96 mg of caffeine
So if you switch from coffee to green tea, you’re cutting your caffeine intake by about two-thirds per cup. Four cups of green tea still delivers less caffeine than a single cup of coffee. For context, the FDA considers up to 400 mg of caffeine per day safe for most healthy adults, which works out to roughly four cups of coffee or about 13 cups of green tea.
Not All Green Tea Is the Same
The 29 mg figure is a useful average, but green tea comes in many forms, and they vary more than you might expect. Data from Japan’s Ministry of Education shows wide differences across common varieties. Gyokuro, a shade-grown premium tea, tops the list at around 160 mg per serving. Sencha, the most common everyday green tea, sits at about 20 mg. Genmaicha (green tea blended with roasted rice) comes in lowest at around 10 mg. Hojicha, a roasted green tea, falls in the same range as sencha.
Then there’s matcha, which works differently from other teas because you consume the entire ground leaf rather than steeping and discarding it. A standard serving of matcha contains about 30 mg of caffeine, comparable to regular brewed green tea. But matcha servings are small (about 1 gram of powder), and many café-style matcha drinks use two or three times that amount, pushing caffeine closer to 60 to 90 mg per drink.
Coffee Varies Just as Much
The type of coffee bean and the brewing method both change the caffeine content dramatically. Robusta beans contain 2.2 to 2.7% caffeine by weight, while Arabica beans (the kind most specialty roasters use) contain only 1.2 to 1.5%. A cup brewed with Robusta beans can deliver nearly double the caffeine of the same cup made with Arabica.
Brewing method matters too:
- Drip coffee (8 oz): ~95 mg
- Espresso (1 oz shot): ~63 mg
- Cold brew (8 oz): ~150 mg
Espresso has the highest caffeine concentration per ounce, but because it’s served in small shots, a full cup of drip coffee or cold brew actually delivers more total caffeine. Cold brew is the outlier here. The long extraction time (often 12 to 24 hours) pulls significantly more caffeine from the grounds, making an 8-ounce cold brew roughly 50% stronger than the same size drip coffee.
How Brewing Changes Your Green Tea
With green tea, you have more control over caffeine than you might realize. Research published through the American Chemical Society found that water temperature is the single biggest factor in caffeine extraction. Tea steeped at boiling (100°C) released caffeine at the highest rate, while cooler water (50°C or 20°C) extracted noticeably less. Steeping time matters too: caffeine levels rise during the first several minutes, then plateau. So a quick steep with slightly cooler water (around 70 to 80°C, which is what most green tea packaging recommends anyway) will give you a milder cup. A longer steep in hotter water pushes the caffeine higher.
This is one practical advantage green tea has over coffee. With drip or cold brew, the caffeine content is largely set by the machine or the process. With loose-leaf green tea, adjusting your water temperature and steep time by even a minute or two gives you a meaningful range to work with.
Why Green Tea Caffeine Feels Different
Many people report that green tea produces a calmer, more sustained alertness compared to coffee, even accounting for the lower dose. This isn’t just perception. Green tea contains an amino acid called L-theanine that’s rare in other foods. L-theanine promotes relaxation without drowsiness and has been shown to counteract some of caffeine’s more jittery effects. The combination produces a state that’s often described as alert but calm, focused without the anxious edge that higher-caffeine coffee can bring.
Coffee contains trace amounts of L-theanine at best, so you get caffeine’s full stimulant profile: a sharper spike in energy, but also a higher likelihood of restlessness, elevated heart rate, or a crash a few hours later. If you’re sensitive to those effects, green tea’s lower caffeine paired with L-theanine can be a more comfortable way to stay alert throughout the day.
How Many Cups Fit Within Safe Limits
At 400 mg per day as the generally accepted ceiling for healthy adults, here’s roughly how many servings of each drink that allows:
- Drip coffee: about 4 cups
- Cold brew: about 2.5 cups
- Green tea (sencha-style): about 13 to 20 cups
- Matcha (single-gram serving): about 13 servings
- Gyokuro: about 2.5 cups
Most green tea drinkers will never come close to the daily limit from tea alone. The people who need to pay closer attention are those mixing sources: a morning coffee, an afternoon matcha latte, and an evening cola can add up faster than any single beverage would suggest. If you’re tracking your intake, the simplest approach is to count your coffee cups first (since they contribute the most per serving) and treat green tea as a lower-stakes addition.