Green tea: caffeine, brewing and taste
A cup of green tea (237 ml) usually has 11–29 mg of caffeine, about 20 mg on average (21% of a cup of filter coffee).
At a glance
| Type | Unoxidised tea |
|---|---|
| Caffeine per cup | 11–29 mg |
| mg / 100 ml | 8.4 |
| Cups to reach 400 mg a day | 20 |
| Water temperature | 70–82 °C |
| Steeping time | 1–3 min |
How it is made
Leaves are not oxidised: brief heating (pan-firing in China or steaming in Japan) stops the enzymes that cause oxidation, then the leaves are shaped and dried.
Taste
Usually lighter, fresher and grassier; water that is too hot or steeping that is too long makes it more bitter.
How to brew
Cooler than boiling water, about 70–82 °C, and short: roughly 1–3 minutes.
For caffeine figures we assume 2 g of dry tea per cup (237 ml).
Steeping time and caffeine
Longer steeping releases more caffeine. Calculated for 2 g of tea per cup.
| Time | Caffeine per cup |
|---|---|
| 2 min | 7–19 mg |
| 3 min | 9–25 mg |
| 4 min | 10–27 mg |
| 5 min | 11–29 mg |
When to drink it
Caffeine's half-life is usually 3–7 hours (we use about 5), so after 5 hours roughly half a cup's caffeine can still be in the body. About 100 mg before bed may affect sleep (EUFIC).
Brands and products
Caffeine stated by manufacturers for products of this type (official data only):
Frequently asked questions
How much caffeine is in green tea?
A cup of green tea (237 ml) usually has 11–29 mg of caffeine, about 20 mg on average (21% of a cup of filter coffee).
How do you brew green tea?
Cooler than boiling water, about 70–82 °C, and short: roughly 1–3 minutes. For caffeine figures we assume 2 g of dry tea per cup (237 ml).
Is green tea good in the evening?
A cup has about 20 mg of caffeine. After 5 hours roughly half can remain, so sensitive people may prefer earlier in the day. Some people are more sensitive to caffeine than others.
Also useful
Sources
- IFT Food Technology: Processing, how tea is processed
- KitchenAid: Tea temperatures, a guide to brewing tea
- Ayakdaş & Ağagündüz, Foods 2025;14(13):2313 (68 tea samples)
- Mayo Clinic: Caffeine content for coffee, tea, soda and more
- Nutrition Reviews 2008;66(2):82–90: Psychological effects of dietary components of tea: caffeine and L-theanine
- EUFIC: EFSA opinion on the safety of caffeine (2015)
Brewing temperature and time are typical: manufacturers' instructions may differ. Data checked 2026-10-24. General information, not medical advice.