An 8-ounce cup of brewed coffee contains roughly 96 mg of caffeine, while the same size cup of black tea has about 48 mg. Coffee delivers about twice the caffeine of tea, cup for cup. But those numbers shift dramatically depending on the type of bean, the variety of tea, how you brew it, and where you buy it.
Coffee vs. Tea: The Basic Numbers
For a standard 8-ounce serving, here’s how the most common options compare:
- Brewed coffee: 96 mg
- Black tea: 48 mg
- Oolong tea: 30 to 55 mg
- Green tea: 20 to 45 mg (average around 28 mg)
- White tea: 15 to 40 mg
So even within tea, there’s a wide range. A strong oolong can deliver more than half the caffeine of a cup of coffee, while a delicate white tea might give you only a sixth as much.
What Changes the Caffeine in Your Coffee
The species of coffee bean matters more than most people realize. 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 coffee shops use Arabica, but cheaper blends and instant coffees often include Robusta, which means they can pack a bigger caffeine punch than a pricier single-origin pour.
Brewing method is the other major variable. Standard drip coffee averages around 12 mg of caffeine per ounce. Cold brew concentrate runs higher, closer to 17 mg per ounce, because the long extraction time (usually 12 to 24 hours) pulls more caffeine from the grounds. If your cold brew is served undiluted, a 16-ounce glass could easily top 270 mg.
Chain coffee shops illustrate how much real-world caffeine can vary from the textbook average. A 16-ounce grande from Starbucks contains 315 to 390 mg of caffeine, while a same-size regular coffee from Panera has about 189 mg. Same cup size, roughly double the caffeine at one chain versus another.
What Changes the Caffeine in Your Tea
Steeping time and water temperature have a massive effect on how much caffeine ends up in your cup. Research published in the Journal of Chemical Education measured caffeine extraction from tea at different temperatures and times, and the differences are striking. Tea steeped for one minute in boiling water yielded about 25 mg per 8-ounce cup. That same tea steeped for three to five minutes at the same temperature jumped to 46 to 70 mg. Steep your tea in lukewarm water for just a minute and you’ll get barely 1 to 2 mg.
This means a quickly dunked tea bag gives you a fraction of the caffeine that a long, hot steep does. If you’re trying to cut back on caffeine, shorter steeping at lower temperatures makes a real difference. If you want more of a kick, let it sit longer.
Espresso vs. Matcha: A Closer Match
Espresso and matcha are worth comparing separately because they’re both concentrated. A single espresso shot averages about 63 mg of caffeine in just one ounce. A typical serving of matcha (1 to 2 grams of powder whisked into water) delivers roughly 60 to 80 mg. So matcha actually matches or slightly exceeds espresso on a per-serving basis, even though tea as a category is lower in caffeine than coffee.
The reason: with matcha, you’re consuming the entire ground tea leaf rather than steeping and discarding it. That means you get all the caffeine the leaf contains, not just what dissolves into water.
Why Tea Feels Different Than Coffee
Many people report that tea gives them a smoother, more sustained energy boost compared to coffee, even when the caffeine amounts are similar. The likely explanation is a compound called L-theanine, an amino acid found naturally in tea leaves but not in coffee. A cup of green tea contains roughly 8 to 30 mg of L-theanine alongside its caffeine.
L-theanine promotes calm focus. When paired with caffeine, it improves cognitive performance and accuracy on demanding tasks while keeping blood pressure and heart rate steadier than caffeine alone. It also helps prevent the classic caffeine crash by reducing the jitteriness and sleep disruption that higher caffeine doses can cause. This is why a cup of tea with 50 mg of caffeine can feel noticeably different from a half cup of coffee with the same amount.
How Many Cups Fit in a Day
The FDA considers up to 400 mg of caffeine per day a safe amount for most healthy adults. In practical terms, that’s about four standard 8-ounce cups of brewed coffee, or roughly eight cups of black tea. But if you’re ordering 16-ounce coffees from a chain, you could hit that ceiling in a single large cup.
Here’s a quick way to think about your daily total:
- 4 cups of drip coffee ≈ 384 mg
- 8 cups of black tea ≈ 384 mg
- 2 espresso shots + 2 cups of green tea ≈ 182 mg
- 1 Starbucks grande ≈ 315 to 390 mg
If you drink a mix of coffee and tea throughout the day, adding up the individual servings gives you a more accurate picture than guessing. People who are sensitive to caffeine or who notice sleep disruption, anxiety, or a racing heart may feel best well below the 400 mg threshold.
Decaf Is Not Zero Caffeine
Decaffeinated coffee and tea still contain small amounts of caffeine. The decaffeination process removes most of it, but not all. An 8-ounce cup of decaf coffee typically has 2 to 15 mg of caffeine, and decaf tea ranges from 1 to 5 mg. For most people this is negligible, but if you’re extremely sensitive or drinking several cups of decaf per day, it adds up.