Tea Caffeine Calculator

A 250 ml cup of tea holds somewhere between zero and about 85 mg of caffeine. Herbal infusions — chamomile, rooibos, peppermint, fruit blends — contain none at all, because they are not made from the tea plant. Everything from Camellia sinensis does: white, green, oolong, black and pu-erh are all the same species, and the differences between them come from how the leaf was picked and processed, not from a caffeine switch.

The old belief that black tea is strong and green tea is gentle does not survive contact with the numbers. Matcha and gyokuro sit at the top of the table because you drink the whole shaded leaf or a very concentrated infusion of it; plenty of black teas sit in the middle. Bud-heavy teas of any colour tend to carry more caffeine than leaf-heavy ones, since the plant concentrates caffeine in the youngest growth as an insecticide.

How you brew matters as much as what you brew. Hotter water and longer steeping pull out more caffeine, and more leaf per cup does the obvious thing. A 60-second gong fu infusion of oolong gives you far less caffeine than a four-minute Western mug of the same leaf — though you will probably drink six of them. The figures in this table are for one 250 ml cup at the recommended ratio, temperature and time, which makes them comparable to each other rather than to a laboratory maximum.

For context, the US Food and Drug Administration cites 400 mg a day as an amount not generally associated with negative effects for healthy adults — around five strong cups of tea, or four coffees. Tea also carries L-theanine, an amino acid that is widely reported to smooth out the alertness curve, which is why a cup of sencha feels different from an espresso with similar caffeine content. If sleep is the concern, the cut-off calculator below is more useful than the milligrams alone.