Green tea vs black tea: caffeine compared
Green tea has 29 mg of caffeine per 8 oz cup. Black tea has 48 mg per 8 oz cup.
Per serving black tea is ahead: 48 mg against 29 mg, about 65% more. Per 100 ml black tea is ahead: 20 mg against 12 mg, about 65% more.
| Green tea | Black tea | |
|---|---|---|
| Serving | 8 oz cup (240 ml) | 8 oz cup (240 ml) |
| Caffeine per serving | 29 mg | 48 mg |
| Caffeine per 100 ml | 12 mg | 20 mg |
| Caffeine per fl oz | 3.5 mg | 5.9 mg |
| In the same 12 oz (355 ml) | 43 mg | 71 mg |
| Share of the 400 mg daily limit | 7% | 12% |
| Peak level, 45 minutes in | 26 mg | 44 mg |
| Time to fall below 40 mg | already below | 1 and a half hours |
| Latest for an 11 pm bedtime | any time | 9:18 pm |
| Servings to reach 400 mg | 13.8 | 8.3 |
What the numbers mean
Green and black tea come from the same plant. Black tea is fully oxidised and usually brewed hotter and longer, and that, more than the leaf, is why it has more caffeine in the cup.
Brewing can reverse the order. A green tea left for five minutes in boiling water will beat a black tea dunked for one. Both are gentle next to coffee: black tea is half a mug of filter coffee, and green tea is low enough to stay under the sleep threshold on its own.
The full page for each
Common questions
Which has more caffeine, green tea or black tea?
Black tea. One 8 oz cup holds 48 mg, against 29 mg in one 8 oz cup of green tea: about 65% more.
Which is the better choice late in the day?
Green tea. One serving stays under 40 mg, so it can be had at any hour. For an 11 pm bedtime black tea needs to be finished by 9:18 pm.
How many servings of green tea equal one black tea?
About 1.7. One 8 oz cup of black tea holds 48 mg and one 8 oz cup of green tea holds 29 mg.
How many can I have in a day?
Going by the 400 mg daily limit for healthy adults: about 13 servings of green tea or 8 of black tea, if that is the only caffeine you have. Anything else with caffeine in it counts toward the same limit.
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Where these numbers come from
Every figure is calculated with the model the Cira app uses: caffeine peaks 45 minutes after you take it and halves every 5.7 hours, 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. These are averages. Smoking, pregnancy, the contraceptive pill and some medicines change how fast you clear caffeine. How the numbers are worked out.
