How much theanine and caffeine are in green and black tea?

A cup of green or black tea contains roughly 10 to 30 mg each of theanine and caffeine, depending on how it is brewed. In a 2025 study of commercial teas, 2 g of tea brewed in 200 mL of water at 80 °C for 2 minutes gave about 13 mg of theanine and 11 mg of caffeine for green tea, and 12 mg of theanine and 14 mg of caffeine for black tea. Brewing for 10 minutes raised both. White, oolong and pu-erh teas had much less theanine. Matcha, the whole powdered leaf, had 9.85 mg of theanine and 16.1 mg of caffeine per gram of powder.

In short:

• Green and black tea: the most theanine of the six types in one study, about 12 to 23 mg per 200 mL
• Caffeine per cup: about 4 to 53 mg per 200 mL across tea types and brewing conditions
• Brewing time: longer brewing raised both theanine and caffeine
• Water temperature: hotter water raised caffeine significantly only in oolong tea; theanine stayed about the same
• Matcha: one study found that shading tea plants raised theanine and caffeine in the leaf
• Thai tea: Assam and Chinese varieties grown in the north; miang is a fermented tea leaf

This article lists how much theanine and caffeine different teas contain and how brewing changes the amounts. For what theanine is and how it compares with GABA, see What are GABA and theanine, and which foods have them?

What are theanine and caffeine in tea?

Both come from the tea plant, Camellia sinensis, and both dissolve into the water when tea is brewed. They are different kinds of molecule.

Two molecules at a glance

Source: PubChem entries for L-theanine and caffeine.

Green, black, oolong: same plant, different processing

Green, white, yellow, oolong, black and pu-erh teas all come from the same plant. What differs is how the leaves are processed, especially how far they oxidise (often called fermentation in tea). The Turkish study described below groups them this way: green and white tea undergo minimal oxidation, oolong and yellow tea moderate oxidation, and black and pu-erh tea high oxidation. Its authors note that theanine is generally higher in unfermented teas such as green tea and tends to decrease as fermentation progresses.

How much theanine and caffeine is in a cup of tea?

A 2025 study from Acıbadem and Gazi Universities in Turkey bought commercial teas of six types and brewed 2 g of each in 200 mL of water, about one cup, at 80 °C or 100 °C for 2, 5 or 10 minutes. It then measured theanine and caffeine in the brewed tea.

Six types of tea, brewed the same way

Brewed at 80 °C for 2 minutes, 2 g of tea in 200 mL. Source: Ayakdaş and Ağagündüz (2025), Tables 2 and 4.

Green and black tea had significantly more theanine than the other four types. Black and yellow tea had the most caffeine at this setting, and pu-erh was similar to black tea. The limits: the teas were bought in Turkey, the number of samples for some types was small (two yellow and two pu-erh teas), and amounts varied widely within each type.

Brewed tea and coffee in the USDA database

The US Department of Agriculture's FoodData Central lists caffeine per 100 g of the brewed drink, which is close to 100 mL.

The UK's NHS gives 75 mg of caffeine for a cup of black or green tea and 100 mg for a cup of instant coffee. The NHS gives these as estimates per cup. The US FDA gives typical amounts for a 12-fluid-ounce drink (about 355 mL): 37 mg for green tea, 71 mg for black tea and 113 to 247 mg for regular brewed coffee.

Does brewing time or water temperature change the amount?

Yes. The Turkish study tested both, and they acted differently on the two compounds.

Brewing time

Longer brewing significantly raised both caffeine and theanine. For green and black tea brewed at 80 °C:

Figures per 200 mL (2 g of tea). Source: Ayakdaş and Ağagündüz (2025), Tables 2 and 4.

In both teas, caffeine kept rising up to 10 minutes, while theanine rose mainly between 2 and 5 minutes.

Water temperature

Water at 100 °C instead of 80 °C changed caffeine more than theanine, although the difference was statistically significant only for caffeine in oolong tea. At 2 minutes, caffeine in oolong tea went from about 4 mg to 14 mg per 200 mL, and in white tea from 5.8 mg to 16 mg. Theanine stayed about the same: 13 mg and 12 mg for green tea, 12 mg and 13 mg for black tea.

Figures per 200 mL (2 g of tea). Source: Ayakdaş and Ağagündüz (2025).

Tea bags and loose leaf

For black tea, the same study compared cup-sized tea bags with loose leaf. At 80 °C, cup-sized bags gave 20, 30 and 38 mg of caffeine per 200 mL after 2, 5 and 10 minutes, and loose leaf 15, 23 and 26 mg.

How much theanine and caffeine is in matcha?

Matcha is different from brewed tea because you drink the whole powdered leaf rather than a water extract.

Matcha powder

A 2022 study from Tomas Bata University in Zlín, Czech Republic, measured 16.1 mg of caffeine, 9.85 mg of theanine and 0.27 mg of theobromine per gram of matcha powder. Because matcha is drunk as a suspension, the amount in a bowl depends on how many grams of powder are used.

The units differ, so the rows describe different things: a gram of powder that is eaten whole, and a cup of water that has extracted part of what was in 2 g of leaves.

How does shading change the leaves?

A 2022 study from Guizhou University in China, which studied shading as used in matcha production, grew tea plants in the open and under 85% and 95% shade, and found that shading raised theanine and caffeine and lowered some catechins (epicatechin and epigallocatechin) in the leaves. The amount in a given matcha therefore depends partly on how the tea plants were grown.

What tea is grown in Thailand?

Tea is grown in northern Thailand. A 2021 study from Chiang Mai University explains that two varieties are cultivated there: Assam tea (Camellia sinensis var. assamica), which has larger leaves, and Chinese tea (Camellia sinensis var. sinensis).

Miang, the fermented tea leaf of the north

The same study describes miang (เมี่ยง) as a traditional Lanna fermented tea leaf made from the Assam variety. The fresh leaves are steamed, bunched and fermented for 13 days to 4 months, and the finished miang ranges from yellow-green to dark green and from tart to sour in taste. It is a product of the northern provinces, including Chiang Rai, Chiang Mai, Nan, Lampang, Phrae, Phayao and Mae Hong Son. In 2007, 77% of the fresh tea leaves produced in Thailand were made into dried tea and 23% into miang.

Source: a study by Sampanvejsobha and colleagues of miang collected from markets in Chiang Mai, Chiang Rai and Phrae, as cited by the Chiang Mai University team (2021). The limits: these are figures for miang leaves, which are eaten rather than brewed, and they come from market samples in three provinces.

What daily caffeine figures do health authorities give?

Theanine and caffeine are not nutrients with a Thai Reference Daily Intake (Thai RDI), so there is no recommended daily amount for either in Thailand. For caffeine, some health authorities give reference figures, as follows.

The US Food and Drug Administration (FDA) says 400 mg is about two to three 12-fluid-ounce cups of coffee, and that people differ widely in how sensitive they are to caffeine and how fast they clear it. Some medical conditions and some medicines can make people more sensitive. The FDA lists coffee, tea and chocolate as well-known sources of caffeine and advises considering all sources of caffeine in the diet.

Amounts in tea vary a lot

The figures in this article come from different countries, tea types and methods, and the amount in your cup depends on the leaf, the amount used, the water temperature and the brewing time. A single number for "theanine in tea" or "caffeine in tea" is therefore only a rough guide.

Who should talk to a doctor or pharmacist?

People who take regular medication

The FDA says some medicines can make people more sensitive to caffeine. If you take medication regularly, ask a doctor or pharmacist whether you should limit caffeine from drinks.

Pregnant and breastfeeding women

The FDA recommends that people who are pregnant, trying to become pregnant or breastfeeding talk to a health care provider about whether they need to limit caffeine. If you are pregnant or breastfeeding, ask a doctor or pharmacist how much caffeine from drinks is right for you.

Dietary supplements are not intended to prevent, treat or cure any disease.