How Many Mg Of Caffeine In a Cup Of Tea? | Tea vs Coffee

A standard 8-ounce cup of black tea contains about 47 mg of caffeine, though amounts can range from 14 mg to 70 mg depending on the type of tea.

You probably assume a cup of tea has far less caffeine than coffee—and you’re mostly right. But the difference isn’t as wide as many people think, and not all teas are created equal. A quick Google often spits out a single number, leaving you wondering why your morning cuppa sometimes gives you a jolt and other times barely registers.

The honest answer is that “a cup of tea” covers a huge range. The type of leaf, how long you steep, even the water temperature all shift the final caffeine count. This article breaks down the numbers so you know exactly what you’re drinking—and how it stacks up against your coffee habit.

The Typical Caffeine Content In Black Tea

Black tea is the most common tea drunk in Western countries, and it’s the benchmark when people ask about caffeine in tea. An 8-ounce (240 ml) cup of brewed black tea contains about 47 mg of caffeine, according to Mayo Clinic data. That’s roughly half the caffeine found in the same size cup of brewed coffee, which sits around 95 mg.

But 47 mg is an average, not a guarantee. Depending on the specific black tea blend and how it’s prepared, the same cup can deliver as little as 14 mg or as much as 70 mg. A brisk English breakfast tea brewed strong will land on the higher end, while a lighter Darjeeling might fall toward the lower side.

For context, an 8-ounce cup of green tea contains about 29 mg of caffeine. White tea and oolong tea fall somewhere between green and black, though the exact numbers vary by source and brewing conditions.

Why The Numbers Vary By Cup

You’ve probably noticed that one tea guide says 40 mg and another says 60 mg for the same type of tea. This variation isn’t a mistake—it reflects real differences in how tea is grown, processed, and brewed. The caffeine content of a tea leaf changes with the plant variety, the season it was harvested, and even which part of the leaf was plucked.

Then there’s the brewing factor, which is the biggest source of confusion. If you and your neighbor both use the same black tea bag but one of you steeps for five minutes and the other for one minute, your caffeine totals will differ. That’s why you see ranges like 40–79 mg for black tea in many consumer guides.

• Steeping time: Longer steeping extracts more caffeine. A 1-minute steep might pull out half the caffeine that a 5-minute steep would.
• Water temperature: Hotter water speeds up extraction. Black tea is typically brewed near boiling, while green tea uses cooler water, partly to avoid bitterness and partly because less caffeine is released.
• Leaf size vs. tea bags: Smaller tea particles (like those in most tea bags) steep faster, meaning they can release caffeine more quickly than whole loose leaves.
• Tea type and processing: Black tea is fully oxidized, which may affect caffeine content compared to minimally oxidized white or green teas, though the plant variety matters more than oxidation level.

If you’re sensitive to caffeine, these variables are worth paying attention to. A short steep with cooler water can dramatically lower the caffeine punch of your cup.

How Tea Types Compare: Black, Green, White, And Oolong

Different tea types come from the same plant—Camellia sinensis—but processing and leaf selection create real differences in caffeine. The table below summarizes typical caffeine ranges for standard 8-ounce cups brewed under typical conditions.

For a deeper look at the numbers behind these averages, the black tea caffeine content page from Mayo Clinic provides the caffeine counts used in the table above. Notice that green tea can sometimes creep close to black tea’s lower end, especially if it’s brewed long and hot.

What Affects Caffeine Extraction In Your Cup

Even if you pick a low-caffeine tea, the way you brew it can push the final number up or down. These four factors have the biggest impact on how much caffeine actually ends up in your mug.

1. Steeping time: A 3-minute steep is standard for black tea. Going to 5 minutes can roughly double the caffeine extracted compared to a 1-minute steep.
2. Water temperature: Boiling water (212°F) pulls caffeine faster than water at 175°F. If you want a lower-caffeine green tea, use cooler water and steep briefly.
3. Tea-to-water ratio: More leaves or a second tea bag mean more caffeine. A restaurant-style mug often uses two bags to make a stronger brew.
4. Agitation: Squeezing the tea bag or stirring frequently can speed up extraction. A passive steep with the bag floating freely will release caffeine more slowly.

If you’re trying to limit caffeine but still want tea, try steeping green or white tea for just 1–2 minutes at a lower temperature. You’ll still get flavor, but with significantly less stimulant.

Tea Caffeine Compared To Coffee And Other Drinks

The most common comparison people want is tea versus coffee. The table below lines up the caffeine content of popular beverages for an 8-ounce serving.

For a broader view of how tea compares across different varieties, the black tea caffeine average page on Healthline offers a solid overview. Keep in mind that coffee’s 95 mg is an average too—some coffee blends can hit 150 mg per 8 ounces, especially darker roasts or espresso-based drinks.

If you’re watching your caffeine intake, replacing one cup of coffee with black tea cuts your intake by about half. Replacing it with green tea cuts it by roughly two-thirds.

The Bottom Line

Most people can safely drink tea without worrying about exceeding the 400 mg daily limit that experts consider safe for healthy adults. Even six cups of black tea at 47 mg each would only total 282 mg. The real takeaway is that your cup’s caffeine content depends far more on brewing habits than on the tea type alone.

If you’re trying to reduce caffeine but still want flavor, try a short steep of green or white tea—you’ll get the taste with less of a lift. A food safety expert or registered dietitian can help tailor your caffeine choices to your health goals and any medications you take.