Yes, tea contains caffeine. An 8-ounce cup of brewed black tea has about 48 mg of caffeine, while green tea has about 29 mg. That’s roughly half to a third of what you’d get from a same-sized cup of coffee, which typically lands between 80 and 100 mg. The exact amount in your cup depends on the type of tea, how hot your water is, and how long you let it steep.
How Much Caffeine Each Type Contains
All “true” teas come from the same plant, Camellia sinensis. Black, green, white, and oolong are all the same leaf, just processed differently. Because they share a plant, they all contain caffeine naturally. According to Mayo Clinic data, here’s what a standard 8-ounce cup delivers:
- Black tea: 48 mg
- Green tea: 29 mg
- Bottled black tea (ready-to-drink): 26 mg
- Decaf black tea: 2 mg
White and oolong teas fall somewhere in between, generally ranging from 15 to 40 mg per cup depending on the specific product and preparation. White tea is often assumed to be low in caffeine, but that’s not always accurate. Teas made from young buds and tips, which many white teas are, can actually be higher in caffeine than teas made from mature leaves.
Why Young Leaves Have More Caffeine
Caffeine acts as a natural pesticide in the tea plant, and the plant concentrates it most heavily in its youngest, most vulnerable parts. Research on tea grown in Hawaii found that caffeine levels decrease as the leaf ages, with the bud containing the most caffeine, followed by the first leaf, then the second. This means a tea labeled “tippy” or made from buds and young shoots can pack a bigger caffeine punch than one made from older, larger leaves, regardless of whether it’s a black, green, or white tea.
Steeping Time and Temperature Change Everything
The caffeine in your cup isn’t fixed by the tea type alone. How you brew it matters enormously. A study published in the Journal of Chemical Education measured caffeine extraction from black tea at different temperatures and times, and the differences were dramatic.
At boiling temperature (100°C), steeping for just one minute produced about 25 mg of caffeine per 8-ounce cup. Letting that same tea steep for six minutes nearly doubled the yield to about 47 mg. But drop the water temperature to 50°C (roughly the temperature of hot tap water), and a one-minute steep extracted only 6 mg, while six minutes pulled out about 30 mg. At room temperature, one minute of steeping released a mere 1.4 mg.
The practical takeaway: if you want less caffeine from the same tea, use cooler water and steep for a shorter time. If you want a stronger caffeine kick, use boiling water and let it sit longer.
Why Tea Feels Different From Coffee
Many tea drinkers report feeling alert but calm after a cup of tea, without the jittery edge that coffee sometimes brings. This isn’t just perception. Tea contains an amino acid called L-theanine that appears to soften caffeine’s stimulating effects. Animal studies have shown that L-theanine can inhibit the excitatory activity caffeine produces in the brain.
One particularly interesting finding: in a study comparing tea to a control drink matched for the same caffeine level, participants who drank tea had lower cortisol (the body’s primary stress hormone) after a stressful task. Caffeine alone typically raises cortisol, especially under stress. Something in tea was producing the opposite effect. Participants also reported feeling more relaxed. Researchers concluded that beverages combining L-theanine and caffeine have a genuinely different effect on the body than caffeine alone.
This is why many people who feel overstimulated by coffee can drink tea comfortably throughout the day. The caffeine is still there, doing its job, but L-theanine takes the sharp edges off.
Herbal Tea Is a Different Story
Herbal teas like chamomile, peppermint, rooibos, and hibiscus contain zero caffeine. They aren’t made from the Camellia sinensis plant at all. They’re infusions of other plants, flowers, or roots, which is why the industry sometimes calls them “tisanes” rather than teas.
There are a few notable exceptions. Yerba mate, made from a South American holly plant, contains roughly 1 to 1.2% caffeine by dry weight, which translates to about 30 to 50 mg per cup depending on preparation. Guayusa, another South American plant, is even higher at 3 to 4% caffeine by weight. Both are sometimes shelved alongside tea, so if you’re avoiding caffeine entirely, check whether your “herbal” tea is actually made from one of these plants.
How Tea Fits Into Daily Caffeine Limits
The FDA considers up to 400 mg of caffeine per day safe for most healthy adults. At 48 mg per cup, you could drink about eight cups of black tea before hitting that ceiling. Green tea gives you even more room. For most people, tea is one of the easiest caffeinated beverages to enjoy without worrying about overdoing it.
Decaf tea isn’t completely caffeine-free, though. It still contains about 2 mg per cup. That’s negligible for most people, but worth knowing if you’re extremely sensitive to caffeine or avoiding it for medical reasons.