Green Tea Caffeine: Comprehensive Nutrition Guide
A 240 ml cup of brewed green tea contains 28 mg of caffeine.
- 240 ml brewed green tea = 28 mg (11.7 mg/100 ml).
- Matcha (whole-leaf powder) is higher: 70 mg per 240 ml serving.
- Caffeine halves in the body about every 5.7 hours; from 28 mg, ~14 mg remains at 5.7 h and ~6.5 mg after 12 h.
- FDA recommends up to 400 mg/day for healthy adults; pregnancy guidance is ~200 mg/day.
Caffeine levels in different green tea types
Brewed green tea (standard cup, 240 ml) is low-caffeine compared with most coffees: the dataset value is 28 mg. Matcha is an exception because you ingest the leaf powder; matcha is listed as 70 mg per 240 ml serving. White, oolong and black teas sit between green tea and coffee in caffeine content (see comparison table).
Why matcha is higher
Matcha uses the whole leaf ground into the water, so you consume the leaf’s full caffeine content rather than just the infusion. That explains the ~2.5× higher caffeine vs a brewed green tea cup in the dataset.
Factors that change green tea caffeine content
Caffeine in a cup of green tea is not fixed; three variables dominate:
- Leaf quantity and particle size: more grams of tea or powdered leaf (matcha) raises mg per cup.
- Steep time and water temperature: longer steeping and hotter water extract more caffeine. Bagged tea (smaller particles) releases caffeine faster than whole-leaf.
- Multiple infusions: first infusion contains the most caffeine; subsequent steeps deliver progressively less.
Laboratory values like the USDA/US FoodData Central (which reports brewed green tea at ~28 mg per 240 ml) reflect typical household brewing, not every possible preparation.
Comparing green tea to other drinks
Quick reference: green tea is low compared with coffee, energy drinks and many cafe beverages. Below are dataset values for common drinks so you can compare mg per serving.
| Drink (serving) | Caffeine (mg) |
|---|---|
| Green tea (240 ml) | 28 mg |
| Matcha (1 tsp, 240 ml) | 70 mg |
| Black tea (240 ml) | 47 mg |
| Oolong tea (240 ml) | 37 mg |
| White tea (240 ml) | 16 mg |
| Drip coffee (240 ml) | 96 mg |
| Espresso (single, 30 ml) | 63 mg |
| Cold brew (240 ml) | 200 mg |
| Red Bull (250 ml) | 80 mg |
| Coca-Cola (355 ml) | 34 mg |
Caffeine decay and timing — sleep considerations
Population-average half-life of caffeine is about 5.7 hours. That means caffeine concentration falls exponentially; rough remaining fractions: 3 h ≈ 69%, 6 h ≈ 48%, 9 h ≈ 33%, 12 h ≈ 23% of the original dose.
Below are computed residues for both a standard brewed green tea (28 mg) and matcha (70 mg) so you can plan intake relative to bedtime.
| Time after drinking | Green tea (28 mg) | Matcha (70 mg) |
|---|---|---|
| 0 h (immediately) | 28.0 mg | 70.0 mg |
| 3 h | ~19.3 mg | ~48.3 mg |
| 5.7 h (≈1 half-life) | 14.0 mg | 35.0 mg |
| 6 h | ~13.6 mg | ~33.9 mg |
| 9 h | ~9.5 mg | ~23.9 mg |
| 12 h | ~6.5 mg | ~16.3 mg |
Practical takeaway: a single brewed green tea in the afternoon leaves only milligrams of caffeine by bedtime for most people, but matcha and multiple cups can add up and affect sleep for sensitive people.
Health context and safety limits
Guidelines: the U.S. FDA and EFSA place common adult limits around 400 mg/day of caffeine for healthy adults as a general upper boundary; many organizations advise lower limits during pregnancy (~200 mg/day). The American Academy of Pediatrics advises that adolescents should limit or avoid routine caffeine. These authorities (FDA, EFSA, Mayo Clinic, AAP) are reliable reference points when planning intake.
Sensitivity varies: some people experience anxiety, palpitations or sleep disruption at low doses. People taking certain medications or with cardiac conditions should consult a clinician. This page is informational, not medical advice.
Decaffeinated green tea and alternatives
Decaffeinated green tea exists, but decaf is rarely 0 mg: residual caffeine varies by method and brand. Laboratory reports show a small residual amount in decaffeinated teas; if you need to avoid caffeine entirely choose herbal tisanes labeled caffeine-free. Always check packaging and, when precise tracking matters, log servings into an app such as CoffeeLog to total daily intake.
For lower-caffeine options, choose a shorter steep, cooler water, smaller leaf amounts or switch to white tea (dataset: 16 mg per 240 ml) or herbal blends.
How to use this information
If you want to keep caffeine below a target (for example, 200 mg/day during pregnancy or 100 mg in the evening), add the mg values above. Track cups and timing to estimate residue at bedtime using the half-life values above; CoffeeLog can automate the math and cumulative totals for you. For clinical concerns — pregnancy, heart issues, pediatric guidance — consult your healthcare provider.
Sources cited in-text include USDA FoodData Central for tea values, the U.S. Food and Drug Administration and EFSA for intake limits, and clinical guidance summarized by the Mayo Clinic and the American Academy of Pediatrics.
Frequently asked questions
How much caffeine is in a cup of green tea?
A standard 240 ml cup of brewed green tea contains 28 mg of caffeine according to FoodData Central.
Is matcha higher in caffeine than brewed green tea?
Yes — matcha is higher because you consume the leaf. Dataset value: 70 mg per 240 ml serving versus 28 mg for brewed green tea.
Will green tea keep me awake at night?
Possibly for sensitive people. Caffeine halves in ~5.7 hours; from 28 mg you’ll have ~14 mg at 5.7 h and ~6.5 mg after 12 h, usually small but still disruptive for some.
How much green tea is safe during pregnancy?
Pregnancy guidance commonly recommends limiting caffeine to about 200 mg/day. A single 240 ml cup of green tea (28 mg) fits easily within that limit, but count other sources.
Does decaffeinated green tea contain zero caffeine?
No. Decaffeinated green tea typically has trace residual caffeine that varies by process; it is not reliably zero. Check brand labelling if you need near-zero intake.
How does green tea compare to coffee for daily limits?
Green tea is low (28 mg/240 ml). Typical brewed coffee (240 ml) is ~96 mg; a single cup of drip coffee contributes much more toward the FDA’s 400 mg/day guideline.