Caffeine in Green tea
A 240 ml cup of green tea holds about 29 mg of caffeine, roughly a third of a mug of filter coffee.
| Caffeine per serving | 29 mg |
| Serving | 8 oz cup (240 ml) |
| Caffeine per 100 ml | 12 mg |
| Share of the 400 mg daily limit | 7% |
| Equal to filter coffee | 0.3 mugs |
| Equal to espresso | 0.5 shots |
How late can you have it?
At 29 mg this sits below 40 mg, the line Cira uses as low enough to sleep on, so on its own it is unlikely to keep you awake. It still adds to whatever else is already in you.
What to know
Green tea is brewed cooler and shorter than black tea, which is most of why it measures lower. The leaf itself is not far apart.
It also carries L-theanine, an amino acid that takes some of the edge off the stimulant without shortening how long it lasts. The alertness feels smoother, the clearance time is unchanged.
Three cups in an evening is about 87 mg, enough to sit above the sleep threshold at bedtime for a slow metaboliser.
Compared with the rest of the tea
| Drink | Serving | Caffeine |
|---|---|---|
| Yerba mate | 8 oz cup (240 ml) | 84 mg |
| Matcha | 8 oz cup (240 ml) | 67 mg |
| Black tea | 8 oz cup (240 ml) | 48 mg |
| Oolong | 8 oz cup (240 ml) | 38 mg |
| White tea | 8 oz cup (240 ml) | 36 mg |
| Chai latte | 10.1 oz cup (300 ml) | 30 mg |
| Green tea | 8 oz cup (240 ml) | 29 mg |
| Herbal tea | 8 oz cup (240 ml) | 0 mg |
Common questions
How much caffeine is in green tea?
Green tea has about 29 mg of caffeine per 8 oz cup (240 ml). That is 7% of the 400 mg daily limit for a healthy adult, or about 0.3 mugs of filter coffee.
Will Green tea keep me awake?
On its own it is unlikely to. At 29 mg it stays below 40 mg, the line Cira uses as low enough to sleep on. It still adds to any caffeine already in you.
How many servings of green tea can I have in a day?
About 13, going by the 400 mg daily limit for healthy adults. That limit covers everything else with caffeine in it too, so the real number is lower on a day with other coffee, tea or cola.
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Where these numbers come from
Caffeine content is the typical value for the serving shown, the same figure the Cira app uses. Brands and brew methods vary, so treat it as a good estimate rather than a measurement of your cup. The 5.7 hour half-life is a typical value for healthy adults, the 40 mg sleep line is a working threshold of the model, and the 400 mg daily limit is the figure used by the European Food Safety Authority and the US FDA. How the numbers are worked out.
