How Much Caffeine Is in Green Tea?
Posted by Ricardo R. Matos, Founder of Tea The World on Apr 4th 2025
Quick answer: An 8 oz cup of brewed green tea usually contains about 20–45 mg of caffeine, roughly a quarter to half of a typical cup of coffee. Matcha, made from whole powdered leaves, usually contains more.
Understanding Caffeine
Caffeine is a natural stimulant found in tea, coffee, cacao, and other plants. It works mainly by blocking adenosine, a brain chemical that builds up during the day and makes you feel sleepy, which is why caffeine helps you feel more alert.
Green Tea vs. Other Drinks (Approximate, per 8 oz)
| Drink | Typical caffeine |
|---|---|
| Brewed coffee | 80–100 mg |
| Black tea | 40–70 mg |
| Green tea | 20–45 mg |
| Matcha (1 tsp powder) | about 60–70 mg |
| White tea | 15–30 mg |
| Herbal tea | 0 mg |
Actual amounts vary widely by product and brewing.
What Affects Caffeine in Green Tea
- Leaf and harvest: Young leaves and buds tend to have more caffeine. Shade-grown teas like gyokuro and matcha are often higher.
- Amount of tea: More leaf means more caffeine.
- Water temperature: Hotter water extracts more caffeine (and more bitterness).
- Steep time: Longer steeps release more caffeine.
- Tea bags vs. loose leaf: Finely broken leaves in bags release caffeine faster.
The Role of L-Theanine
Green tea also contains L-theanine, an amino acid found almost exclusively in tea. Studies of L-theanine combined with caffeine have reported improvements in alertness and attention, which may explain why many people describe green tea’s lift as calmer and smoother than coffee’s.
How Much Green Tea Is Reasonable?
The U.S. FDA cites about 400 mg of caffeine a day as an amount not generally associated with negative effects for healthy adults. That leaves plenty of room for several cups of green tea, though your total caffeine from all sources counts. People who are pregnant, sensitive to caffeine, or have certain health conditions should aim lower and talk with their healthcare provider.
Possible Side Effects
- Too much caffeine can cause jitteriness, a racing heart, or trouble sleeping.
- Green tea on an empty stomach can cause mild upset in some people.
- Tannins can reduce iron absorption from plant foods, so drink tea between meals if you’re watching your iron.
Tips for Choosing and Brewing Green Tea
- For less caffeine, use a little less leaf, cooler water (160–175°F), and a shorter steep (1–2 minutes).
- For a stronger lift, try matcha.
- Enjoy green tea earlier in the day if caffeine affects your sleep.
Try our India Simply Green Tea or fruity Turkish Apricot and Peach Green Tea.
Conclusion
Green tea offers a moderate amount of caffeine with a gentle, focused feel. Knowing what’s in your cup helps you enjoy it at the right time and in the right amount.
Disclaimer: This article is for educational purposes only and does not provide medical advice.