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.

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.

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.

How many cups of green tea equal one cup of coffee?

A 240 ml cup of brewed green tea contains 28 mg of caffeine, and a 240 ml cup of drip coffee contains 96 mg. Therefore, it takes approximately 3.4 cups of green tea to deliver the same caffeine as one cup of drip coffee.

Because coffee preparation methods vary widely in extracted caffeine, the number of green-tea-equivalents changes with the type of coffee. The table below lists several common coffee drinks from the dataset, their caffeine content, and how many 240 ml cups of green tea you would need to match each one.

Even a single 30 ml shot of espresso packs 63 mg, which is more than double the caffeine in a cup of green tea. For a cold brew concentrate at 200 mg per 240 ml, you would need to drink seven standard cups of green tea to reach that level. This is why switching from coffee to green tea can dramatically reduce daily caffeine intake, especially if you previously consumed multiple cups of strong coffee. If you're trying to cut down gradually, blending half a cup of coffee with green tea might be a smoother path—and you can compare green tea and coffee side by side to find a ratio that works for you. The U.S. FDA’s 400 mg daily limit translates to roughly 14 cups of brewed green tea or only about 4 cups of drip coffee, illustrating how much more green tea you can drink while staying within safe boundaries.

Does green tea's L-theanine change the way caffeine feels?

L-theanine is a non-protein amino acid that increases alpha brain wave activity, which is associated with a relaxed but alert mental state. A typical 240 ml cup of green tea provides roughly 20 mg of L-theanine alongside its 28 mg of caffeine, creating a qualitatively different experience from coffee’s sharper stimulant effect.

Caffeine blocks adenosine receptors to promote wakefulness, while L-theanine promotes relaxation by boosting neurotransmitters like GABA and serotonin. This combination often results in what many people describe as “calm focus”—sustained attention without the jitters or anxiety that can accompany an equivalent dose of caffeine from coffee. Researchers have found that when L-theanine and caffeine are taken together, cognitive performance on tasks requiring rapid information processing improves, and self-reported feelings of nervousness drop compared with caffeine alone. Because green tea delivers both compounds naturally in a modest dose, it is a popular choice for those who need to stay alert but dislike the side effects of higher-caffeine drinks. The specific L-theanine content varies by tea grade and shade-growing (used for matcha and gyokuro), with matcha often containing up to 40 mg per cup due to the whole-leaf consumption. If you’re looking for a morning lift without overstimulation, a cup of green tea can provide a smoother entry point than coffee; you can learn more about green tea’s energy and caffeine effects in our detailed guide. And because the caffeine dose is lower, the crash that some coffee drinkers report is usually less pronounced.

Can I drink green tea before a workout?

Yes, green tea can serve as a mild pre-workout because its caffeine content improves strength, endurance, and focus. A 240 ml cup provides 28 mg, which is well below the 200 mg typically found in a standard scoop of pre-workout supplement, but it may be enough for beginners or those sensitive to stimulants.

Caffeine’s ergogenic effect—performance enhancement—has been confirmed by sports science for doses of 3–6 mg per kilogram of body weight. For a 70 kg person, that target range is 210–420 mg; one cup of green tea supplies only a small fraction, so it is unlikely to meet that dose alone. However, matcha (70 mg per cup) comes closer, and drinking two cups (140 mg) approaches a moderate pre-workout dose. Timing matters: caffeine peaks in the bloodstream about 45–60 minutes after ingestion, so drinking it 30–60 minutes before exercise is optimal. Because green tea also contains L-theanine, some athletes report less jitteriness during high-intensity lifts compared with coffee or synthetic pre-workouts. Just be aware that caffeine’s half-life of 5.7 hours means that an afternoon workout session with matcha could still leave ~35 mg in your system by bedtime if you take it at 2 p.m. If your main goal is performance, a caffeine pre-workout guide can help you calculate a dose aligned with your body weight. For those who prefer a more natural source, green tea is a valid option, though the volume of fluid required for a full ergogenic dose might be impractical.

How does green tea caffeine affect blood pressure?

A single cup of green tea can cause a small, temporary increase in blood pressure—typically 3 to 6 mmHg systolic—in people who do not regularly consume caffeine. This effect usually fades as the body develops tolerance with consistent intake.

Caffeine is a vasoconstrictor that can briefly stiffen arteries, leading to a short-term blood pressure bump. However, green tea also contains catechins (antioxidants) that promote endothelial function, and L-theanine may counteract some of the pressor effects. In long-term studies, habitual green tea drinkers often show neutral or even slightly lower blood pressure averages, suggesting that any acute rise is outweighed by the beverage’s overall cardiovascular benefits. The European Food Safety Authority’s 2015 opinion sets a single-dose caffeine safety limit of 200 mg, which is more than seven cups of green tea at once—so normal consumption is well within the safety threshold for acute effects. For people with diagnosed hypertension or those monitoring their blood pressure, moderate green tea intake (1–3 cups daily) is generally considered acceptable, though individuals should follow their physician’s advice. If you track your caffeine to stay within a personalized safe zone, the safe daily limit by body weight tool can help you translate guidelines into practical cup counts. And remember that understanding caffeine dosage levels is key to avoiding unwanted cardiovascular strain.

Is it OK to drink green tea while taking medication?

Green tea contains caffeine and a range of plant compounds, so it can interact with certain prescription and over-the-counter drugs. Because the caffeine dose per cup is low (28 mg), the risk is generally smaller than with coffee, but you still need to check with your healthcare provider about your specific medications.

Caffeine is metabolized primarily through the liver enzyme CYP1A2. Medications that inhibit this enzyme—such as certain fluoroquinolone antibiotics (e.g., ciprofloxacin), oral contraceptives, and some antidepressants—can slow caffeine clearance, effectively prolonging and intensifying its effects. Conversely, drugs that induce CYP1A2 (like rifampin) may speed up metabolism, reducing the impact. Green tea also contains vitamin K, which can interfere with warfarin (a blood thinner), though the amount is small; still, people on anticoagulants are often advised to keep their green tea intake consistent. Additionally, the modest diuretic effect of caffeine may compound with diuretic medications. The Mayo Clinic and other clinical sources recommend limiting caffeine to moderate levels when taking interacting drugs. Because green tea’s 28 mg per cup is a fraction of what coffee delivers, substituting green tea for coffee might be a safer compromise if you’re told to reduce caffeine. For detailed information on how caffeine interacts with health conditions, our caffeine health impacts guide covers many of these topics. Ultimately, the decision is medical, not nutritional—this page is informational and does not replace professional advice.

Bottom line

Green tea is a low-caffeine beverage that provides a gentle lift without the intensity of coffee or energy drinks. A standard 240 ml cup of brewed green tea contains just 28 mg of caffeine, while matcha delivers 70 mg per cup due to whole-leaf ingestion. By comparison, an equal-size cup of drip coffee has 96 mg, and a single espresso shot has 63 mg. The U.S. FDA’s 400 mg daily ceiling translates to approximately 14 cups of green tea—a margin that makes green tea an easy beverage to enjoy throughout the day for most healthy adults.

Caffeine’s population-average half-life of 5.7 hours means that a 28 mg cup leaves only about 6.5 mg in your system after 12 hours. This makes it unlikely to disrupt sleep unless you are highly sensitive or drink multiple cups late in the day. Caffeine’s effect on sleep is well documented; one study found that 400 mg taken 6 hours before bed cut sleep time by over an hour (Drake et al., 2013). For pregnancy, the EFSA 200 mg/day recommendation allows up to seven cups of standard green tea, though a conservative approach of no more than three to four cups is common. The presence of L-theanine in tea smooths the alertness, reducing jitteriness. If you want to track the cumulative effect of your cups, the caffeine half-life calculator can estimate how much caffeine remains at any hour, helping you avoid unintentional late-day stacking. Whether you sip green tea for its flavor, its calm focus, or its health profile, knowing the numbers lets you make informed choices.