Coffee has significantly more caffeine than black tea. An 8-ounce cup of brewed coffee contains roughly 80 to 100 milligrams of caffeine, while the same size cup of black tea delivers around 40 to 70 milligrams. That means coffee typically packs about twice the caffeine punch, though the exact gap depends on how each drink is prepared.
How the Numbers Break Down
For a standard 8-ounce serving, brewed coffee lands in the 80 to 100 mg range for most drip or pour-over methods, with some preparations climbing higher. Instant coffee comes in lower, at about 62 mg per cup. Espresso is more concentrated per ounce but is served in much smaller volumes, so a single shot (about 1 ounce) contains roughly 63 mg.
Black tea sits in a range of about 40 to 70 mg per 8-ounce cup, depending heavily on steeping time and water temperature. A quick one-minute steep in boiling water yields only about 25 mg, while a longer steep of four to six minutes brings the caffeine closer to 45 to 47 mg. The manufacturer labels on most tea boxes cite 46 to 70 mg for a three-to-five-minute steep, which is what most people actually do at home.
Why the Range Is So Wide
Both drinks have a surprisingly large caffeine window, and a few variables explain why.
For coffee, the bean variety matters most. Robusta beans contain about 2.2 to 2.7% caffeine by weight, nearly double the 1.2 to 1.5% found in Arabica beans. Most specialty and grocery-store coffee is Arabica, but cheaper blends and instant coffees often include Robusta, which bumps the caffeine up. Grind size, brew time, and water temperature all play a role too. A longer extraction pulls more caffeine into the cup, which is why cold brew (steeped for 12+ hours) can be surprisingly potent despite using cold water.
For tea, steeping time is the biggest lever you can pull. Research published by the American Chemical Society measured caffeine extraction from tea bags at boiling temperature and found a clear curve: about 25 mg at one minute, 39 mg at two minutes, 43 mg at four minutes, and 47 mg at six minutes. After that, the curve flattens. Steeping for eight minutes produced roughly the same caffeine (45 mg) as six minutes, meaning the leaves had already released most of what they had. Water temperature matters too. Steeping at lukewarm temperatures extracts dramatically less caffeine than boiling water.
Tea Leaves Actually Start With More Caffeine
One fact surprises most people: pound for pound, dried tea leaves contain more caffeine than coffee beans. The reason coffee still wins in the cup is simple math. A typical serving of coffee uses 10 to 12 grams of ground beans, while a tea bag holds only about 2 to 3 grams of leaves. You’re just using a lot more raw material when you brew coffee.
Why Tea Feels Different Than Coffee
Even when the milligram counts are closer than expected, most people report that tea and coffee feel different. That’s not imaginary. Black tea contains an amino acid called L-theanine, which promotes the production of alpha brain waves associated with alert relaxation. When L-theanine and caffeine work together, the result is a calmer, more sustained focus rather than the sharp spike and crash that coffee sometimes causes.
Some studies suggest this combination improves attention and cognitive performance, which is why tea is often described as providing a “smoother” energy boost. If you’re sensitive to the jittery feeling coffee can produce, switching to black tea gives you a moderate dose of caffeine with a built-in buffer.
What This Means for Your Daily Intake
The FDA considers up to 400 mg of caffeine per day safe for most adults. That’s roughly four to five cups of black tea or about two to three standard 12-ounce cups of coffee. Most people are nowhere near that ceiling with tea alone, but coffee drinkers can approach it faster than they realize, especially with large servings. A 16-ounce coffee shop “grande” can easily contain 200 mg or more in a single drink, putting you halfway to the daily limit before lunch.
If you’re trying to cut back on caffeine without giving it up entirely, swapping one or two cups of coffee for black tea is a practical move. You’ll roughly halve your intake per cup while still getting enough to stay alert. And because tea releases its caffeine more gradually thanks to L-theanine, the transition tends to feel gentler than simply drinking less coffee.