A standard tea bag contains roughly 30 to 70 milligrams of caffeine, depending on the type of tea and how you brew it. That’s about half as much as an 8-ounce cup of brewed coffee, which averages 96 milligrams.
Caffeine by Type of Tea
Not all tea bags are created equal. Black tea delivers the most caffeine among common varieties, averaging about 47 to 50 milligrams per 8-ounce cup. Green tea comes in lower, between 30 and 50 milligrams. Oolong falls somewhere in between at 30 to 55 milligrams. White tea sits at the bottom of the true-tea spectrum, with just 15 to 40 milligrams per cup.
These ranges assume you’re using a single standard tea bag (about 2 grams of tea leaves) in 8 ounces of water. “Double strength” bags or pyramid sachets packed with more leaf will push the numbers higher.
Herbal teas like rooibos, chamomile, and peppermint are naturally caffeine-free. They aren’t made from the tea plant at all, so the caffeine question doesn’t apply to them.
How Steeping Changes Your Caffeine
The amount of caffeine that ends up in your cup depends heavily on how long you let the bag sit in water. Caffeine doesn’t dissolve all at once. After one minute of steeping, only about 18% of the available caffeine has been extracted. At three minutes, you’re at roughly 48%. By five minutes, about 69% has made it into the water. Lab measurements of black tea steeped in boiling water show this progression clearly: 25 milligrams at one minute, 39 milligrams at two minutes, 43 milligrams at four minutes, and a peak of about 47 milligrams at six minutes.
After that peak, the caffeine concentration levels off and even dips slightly. Steeping for eight minutes yielded 45 milligrams in the same study, essentially the same as six minutes. So letting your tea sit for 10 or 15 minutes won’t meaningfully increase the caffeine, but it will make the cup more bitter as other compounds continue to dissolve.
Water temperature matters too. Hotter water pulls caffeine out faster. Boiling water (212°F) extracts caffeine much more quickly than cooler water. This is one reason green tea, which is typically brewed at lower temperatures around 175°F, tends to deliver less caffeine per cup even when the leaves themselves contain a similar amount.
Tea vs. Coffee
A cup of brewed coffee contains about 96 milligrams of caffeine per 8 ounces, according to Mayo Clinic data. A cup of black tea brewed the same way delivers about 48 milligrams. So tea gives you roughly half the caffeine hit of coffee, cup for cup. For most people, that makes tea a gentler option for staying alert without the jitteriness that a strong coffee can cause.
The FDA considers up to 400 milligrams of caffeine per day a safe amount for most healthy adults. That works out to roughly 8 cups of black tea, compared to about 4 cups of coffee. Even heavy tea drinkers rarely approach that limit from tea alone.
What About Decaf Tea Bags?
Decaffeinated tea bags still contain small amounts of caffeine, typically 1 to 2 percent of what a regular bag would have. For black tea, that translates to roughly 1 to 2 milligrams per cup. It’s not zero, but it’s low enough that most caffeine-sensitive people tolerate it without trouble. Worth noting: enforcement of decaf labeling is loose, so some products may contain slightly more than expected. If you need to avoid caffeine entirely, herbal teas like rooibos are a more reliable choice since they contain no caffeine at all.
Quick Ways to Control Your Caffeine
- Shorter steep, less caffeine. Pulling the bag after one to two minutes gives you roughly a third of the maximum caffeine. A full five-minute steep gets you close to two-thirds.
- Use cooler water. Brewing at a lower temperature slows caffeine extraction noticeably.
- Choose white or green over black. Switching tea types can cut your per-cup caffeine by 20 to 30 milligrams.
- Skip the second bag. Doubling up on tea bags in one mug roughly doubles the caffeine.
- Go herbal after noon. Rooibos, chamomile, and other herbal infusions are completely caffeine-free and won’t interfere with sleep.