Green Tea Caffeine: A Comprehensive Breakdown
A standard 240 ml cup of brewed green tea contains 28 mg of caffeine.
- 240 ml brewed green tea = 28 mg caffeine (11.7 mg/100 ml).
- Matcha (1 tsp, whisked) = 70 mg, about 2.5× brewed green tea.
- Typical brewed coffee (drip) 240 ml = 96 mg200 mg for context.
- Population-average caffeine half-life ≈ 5.7 hours; after 6 h ~48% remains.
Caffeine levels in standard green tea
The dataset value for a 240 ml (about 8 fl oz) cup of brewed green tea is 28 mg (11.7 mg per 100 ml). That number reflects a typical single steep using loose leaf or a tea bag at standard strength. Compared with other common hot teas in the dataset: black tea 240 ml = 47 mg, oolong = 37 mg, white tea = 16 mg.
Variations across green tea types
Not all green teas are equal. Matcha is powdered whole-leaf tea and delivers the full leaf’s caffeine to the cup—dataset: matcha (1 tsp) = 70 mg. Other named varieties (sencha, gyokuro, bancha) aren’t individually listed in the dataset; their caffeine content depends on leaf choice and preparation. Shade-grown teas (gyokuro) typically concentrate caffeine and L-theanine compared with sun-grown leaves, so expect higher values than 28 mg per 240 ml.
Quick comparison table (dataset values)
| Drink / serving | Volume | Caffeine (mg) |
|---|---|---|
| Green tea (brewed) | 240 ml | 28 |
| Matcha (1 tsp) | 240 ml | 70 |
| Black tea | 240 ml | 47 |
| Oolong tea | 240 ml | 37 |
| White tea | 240 ml | 16 |
| Yerba mate | 240 ml | 85 |
| Drip coffee | 240 ml | 96 |
| Cold brew | 240 ml | 200 |
Factors that change green tea caffeine
Primary variables are leaf type, leaf-to-water ratio, water temperature, steep time and whether you consume the leaf (matcha) or just the infusion. Longer steeping and hotter water extract more caffeine; doubling leaf mass roughly doubles caffeine. Because matcha is powdered whole-leaf, its concentration is higher than a typical infusion of the same volume.
Practical preparation guidance
- To reduce caffeine: use cooler water, shorter steeps (30–60 seconds), or choose white tea (dataset: 16 mg/240 ml).
- To increase caffeine: use more leaf, hotter water, longer steeps, or choose matcha (70 mg) or yerba mate (85 mg).
How caffeine from green tea decays in the body
Caffeine follows first-order elimination with a population-average half-life of about 5.7 hours. That means the amount in your body drops by roughly half every 5.7 hours. Below are concrete remaining-milligram calculations from two real doses in the dataset: 28 mg (brewed green tea) and 70 mg (matcha).
| Time after dose | % remaining (approx) | From 28 mg (mg) | From 70 mg (mg) |
|---|---|---|---|
| 0 hours (ingested) | 100% | 28 | 70 |
| 3 hours | ≈ 69% | 19 | 48 |
| 6 hours | ≈ 48% | 14 | 34 |
| 9 hours | ≈ 34% | 9 | 24 |
| 12 hours | ≈ 24% | 7 | 17 |
Example: after a 240 ml cup of green tea (28 mg), roughly 14 mg remains after 6 hours and about 7 mg after 12 hours. For matcha (70 mg), about 34 mg remains at 6 hours and 17 mg at 12 hours. Individual half-life varies with age, genetics, pregnancy, liver function and concurrent medications.
Health context, safety limits and timing
Authoritative guidance: the U.S. FDA notes about 400 mg/day as a reference upper bound for healthy adults; many organizations advise lower intakes during pregnancy (≈200 mg/day) and the American Academy of Pediatrics discourages caffeine for adolescents. A single cup of brewed green tea (28 mg) is low compared with these limits, but multiple cups or matcha servings can add up.
Practical timing: because about half the caffeine remains after ~6 hours, avoid consuming concentrated green tea (matcha or multiple cups) within 6 hours of your planned bedtime if you are sensitive to sleep disruption. If tracking cumulative intake matters, log servings in an app such as CoffeeLog to see daily totals and timing.
Green tea extracts and supplements
Green tea extracts concentrate polyphenols and sometimes caffeine; the dataset does not list specific extract doses, so read labels. Extracts can deliver substantially more caffeine per serving than a brewed cup, and some high-dose extracts have been associated with rare liver injury reports—consult healthcare professionals before starting high-dose supplements. Always track supplement milligrams the same way you track beverages.
Takeaway and tracking
Brewed green tea is low in caffeine (28 mg/240 ml) compared with coffee. Matcha is meaningfully higher (70 mg per 1 tsp). Use steeping choices to tune caffeine up or down, and remember caffeine lingers: roughly half remains after 5.7 hours. For precise daily totals and timing, log drinks and supplements in CoffeeLog or a similar tracker.
Sources and authorities cited
Data points above come from beverage composition entries (USDA FoodData Central-style dataset) and are presented alongside clinical guidance from the U.S. Food and Drug Administration, European Food Safety Authority, Mayo Clinic and American Academy of Pediatrics for safety context.
Frequently asked questions
How much caffeine is in a cup of green tea?
A standard 240 ml brewed cup of green tea contains 28 mg of caffeine (11.7 mg per 100 ml) according to the dataset used here.
Is matcha higher in caffeine than brewed green tea?
Yes. Matcha (1 tsp, whisked) is 70 mg per the dataset—about 2.5 times the caffeine of a 240 ml brewed green tea (28 mg).
How long does green tea caffeine stay in my system?
Population-average half-life is ~5.7 hours. From 28 mg, roughly 14 mg remains after 6 hours and ~7 mg after 12 hours; individual metabolism varies.
Can pregnant people drink green tea?
Pregnant people are generally advised to limit caffeine to about 200 mg/day. A single 240 ml cup of green tea (28 mg) is low, but multiple servings or matcha can add up—consult your clinician.
Are green tea extracts safe and do they contain caffeine?
Extracts can contain concentrated caffeine and catechins; the dataset doesn’t list extract doses so check labels. High-dose extracts have been linked to rare liver injury reports—consult a healthcare professional before use.