How much caffeine is in green tea?

Steeped green tea has about 30–50 mg of caffeine per cup (~35 mg typical). Green vs black tea compared side by side, coffee and matcha too, and re-steeps.

By PGP Iyer · July 28, 2026 · Updated September 21, 2026 · 9 min read

An 8 oz cup of steeped green tea contains about 30–50 mg of caffeine — typically around 35 mg. That's roughly a third of a cup of coffee (~95 mg) and about two-thirds of a cup of black tea (~50 mg).

What changes how much caffeine ends up in your cup

Green tea's caffeine isn't one fixed number — it's a range, because brewing choices and the leaf itself both move it. The main variables:

• Steep time. Caffeine is one of the fastest compounds to extract from tea leaves, so a longer steep pulls out more of it. A quick 1-minute steep sits toward the low end of the range; a full 3-minute steep pushes toward the high end.
• Water temperature. Hotter water extracts caffeine faster. Green tea is typically brewed at 165–185°F (74–85°C) — cooler than black tea's near-boiling water — which is one reason green tea's typical caffeine lands lower than black tea's, even before steep time is factored in.
• Leaf grade and cultivar. Younger leaves and buds, used in higher grades of sencha and gyokuro, tend to carry more caffeine than older, coarser leaves picked later in the season.
• Loose leaf vs. tea bag. More surface area extracts faster, so finely cut bagged tea can release caffeine a little quicker than whole-leaf tea over the same steep time.
• Amount of leaf used. A heaping teaspoon per 8 oz extracts more caffeine than a level one, the same way a stronger pour-over has more caffeine than a weak one.

These variables move you within green tea's 30–50 mg range for a standard steep — they explain why the number moves within that range rather than why one source says 20 mg and another says 60 mg. A much longer steep or boiling-hot water can push past the top of that range; for exact water-temperature and steep-time targets by tea type, see our green tea steeping time guide.

Green tea vs. coffee, matcha, and black tea

Use the calculator above to compare any drink by the cup or across a full day, or check the static reference table below — the same figures the calculator uses:

Three things stand out. First, green tea and oolong sit close together — both are lightly oxidized (or not at all) and brewed at similar, sub-boiling temperatures, so their caffeine ranges overlap; white tea, brewed the same way, sits just below both rather than matching them. Second, matcha is the outlier among true teas: because you consume the whole ground leaf instead of steeping and discarding it, a standard serving carries close to double steeped green tea's caffeine. Third, an espresso shot and a cup of green tea land in surprisingly different places despite both being small, concentrated pours — espresso's shorter, high-pressure extraction pulls a lot more caffeine out of a lot less liquid.

Worth noting: white tea, which many people assume is the lowest-caffeine "real" tea, sits just below green tea's range rather than far below it — the buds and young leaves used for white tea can carry nearly as much caffeine as sencha, even though white tea is processed less than green tea.

Green tea vs black tea: what actually differs

Caffeine is the smallest difference between the two. Both come from the same plant, Camellia sinensis; what separates them is what happens to the leaf after picking.

Processing. Oxidation is the dividing line. Black tea leaves are rolled to break cell walls, then held in warm, humid air while enzymes turn the leaf dark and develop malty, brisk flavors. Green tea is heat-fixed within hours of picking, which deactivates those enzymes, keeps more chlorophyll and catechins intact, and gives the fresher, vegetal cup. Once a leaf has been heat-fixed it cannot be turned into black tea: the enzymes oxidation depends on are gone.

Compounds, in research terms. Green tea keeps its catechins, and EGCG is the one most studied; a 2023 systematic review pooled 55 randomized trials of green tea supplementation in cardiovascular risk-factor research. Black tea’s oxidation converts most catechins into theaflavins and thearubigins, which have been studied separately, including a 15-trial meta-analysis of black tea consumption and blood cholesterol and a 12-week randomized trial of a theaflavin-enriched extract (an extract, not brewed tea). Green tea also tends to retain more L-theanine than black tea. These are descriptions of what has been studied, not claims about what a cup will do; we do not rank the two teas on health.

Brewing. The lower temperature for green tea is not tradition for its own sake: catechins extract fast and turn bitter in near-boiling water, so 74–85°C keeps the cup sweet. Black tea’s oxidized compounds need hotter water and a longer steep to extract fully, which is why it is brewed at or near a boil for 3–5 minutes. Our brewing temperature guide covers every tea type.

Why green tea caffeine numbers vary online

Search around and you'll find green tea caffeine figures ranging from under 10 mg to well over 60 mg for what's described as a single cup. The gap usually comes down to what's being measured, not a real disagreement about the tea. Some sources report caffeine for a small 6 oz cup; others for a full 8 oz mug. Some quote a light, quick-steeped cup; others quote a strong, long-steeped one. Agricultural products like tea also naturally produce a range rather than one fixed number, since caffeine content shifts with growing conditions, harvest timing, and how the leaf is processed.

This page standardizes on one convention throughout: caffeine per 8 oz cup of steeped green tea, cross-checked against the published tea-caffeine sources cited below. The comparator tool above and every table on this page pull from that same dataset, so the numbers won't drift depending on which section you're reading.

What about a second or third steep?

Every figure on this page is for a single steep of fresh leaves. Re-steeping the same leaves gives you a cup with less caffeine each time, because each infusion can only draw on what the previous one left in the leaf; how much less depends on the leaf, the water temperature and how long the first steep ran. We have not found a published measurement of green tea caffeine by second or third infusion that we would stand behind, so we do not print a third-brew number here. If you want a lighter cup, a short first steep of 30–60 seconds, discarded, is the traditional way to take the edge off before brewing the cup you drink.

Decaf and low-caffeine green tea options

If you want the flavor without the caffeine, two routes get you there. Decaffeinated green tea goes through a process that removes most — not all — of its caffeine, so a decaf cup still carries a small residual amount rather than being truly caffeine-free. Rooibos and herbal tisanes aren't tea at all; they don't come from the Camellia sinensis plant, so they contain 0 mg of caffeine with nothing to remove.

Shorter steep times and cooler water also lower caffeine somewhat without switching teas, though the effect is modest — for a standard steep, brewing technique shifts you within green tea's 30–50 mg range; a much longer or boiling-hot steep can push past it (see above). If you're trying to cut caffeine meaningfully rather than marginally, switching to a decaf green tea or a caffeine-free tisane does more than adjusting steep time on regular green tea.

Green tea, caffeine, and L-theanine

Green tea pairs its caffeine with L-theanine, an amino acid found almost exclusively in tea leaves. Published research has looked at how the two compounds interact together: Kelly and colleagues (2008, Journal of Nutrition) reported that L-theanine combined with caffeine was associated with changes in alpha-band brain activity and attention-task performance compared with either compound alone. That describes what the study measured — it isn't a promise about how any individual cup will make you feel, and responses to caffeine and L-theanine vary by person, tolerance, and how much you drink.

Matcha delivers a higher dose of both caffeine and L-theanine than steeped green tea per serving, since the whole leaf is consumed rather than steeped and discarded — see our full matcha vs green tea comparison for the numbers, or our dedicated L-theanine and caffeine in tea page for the research in more depth.

Is green tea's caffeine a lot?

At roughly 35 mg per 8 oz cup, a single serving of green tea is a modest share of the general daily reference published for healthy adults — the U.S. FDA has cited about 400 mg per day as a level not generally associated with dangerous, negative effects for most healthy adults. That reference covers total caffeine intake across everything you drink in a day, not any single cup, so it's worth counting coffee, tea, and other caffeinated drinks together rather than green tea in isolation. At the ~35 mg typical figure, it would take roughly eleven 8 oz cups to reach that reference point — far more than most people drink in a day, and more a reflection of how mild green tea's caffeine is per serving than a target to aim for. People who are pregnant, caffeine-sensitive, or managing a health condition should talk to a healthcare provider about what caffeine level is appropriate for them.

For a full side-by-side on flavor, prep, and nutrients beyond caffeine, see matcha vs green tea. To see how green tea compares against black tea more broadly, see green tea vs black tea.

This describes published research and general information, not medical or dietary advice.