A 12 oz cup of brewed coffee contains roughly 140 to 245 mg of caffeine, depending on the brewing method, bean type, and roast level. The most common preparation, standard drip or filter coffee, lands around 140 to 250 mg for 12 ounces. That range is wide because coffee is a natural product with dozens of variables affecting the final number in your cup.
The FDA describes 400 mg per day as the general safe limit for most adults, and specifically notes that “about two to three 12-fluid-ounce cups of coffee” falls within that range. So a single 12 oz cup gets you roughly a third to half of your daily budget.
Caffeine by Brewing Method
How you make your coffee matters more than most people realize. The brewing method determines how long water stays in contact with the grounds, how hot that water is, and how finely the coffee is ground, all of which change how much caffeine ends up in your cup. Here’s how the most common methods compare, scaled to a 12 oz serving:
- Drip or filter coffee: 140–250 mg per 12 oz. This is the standard for most home coffee makers and what you’ll get at most diners and offices.
- Percolated coffee: around 300 mg per 12 oz. Percolators cycle hot water through the grounds multiple times, pulling out significantly more caffeine.
- French press: roughly 160 mg per 12 oz. Despite the longer steeping time, the coarse grind used in a French press actually results in slightly less caffeine than drip coffee.
- Cold brew: about 150 mg per 12 oz. Cold water extracts caffeine more slowly, but the long brew time (12 to 24 hours) compensates. Research from Thomas Jefferson University found that cold brew with coarse grounds can actually yield higher caffeine concentrations than hot brew with the same grind, because the extended contact time allows more complete extraction.
- Espresso: 47–64 mg per 1 oz shot. Ounce for ounce, espresso is the most concentrated, but since servings are small, a 12 oz drip coffee delivers far more total caffeine than a single or even double shot.
A commercial example: Folgers Classic Roast, brewed with their recommended two tablespoons to make 12 oz, contains 120 to 160 mg of caffeine.
Why the Range Is So Wide
That 100+ mg spread between the low and high end of drip coffee isn’t a guess. It reflects real variation in what ends up in your mug. Three factors drive most of it.
Bean Variety
The two main species of coffee bean have dramatically different caffeine levels. Robusta beans contain about 2.2 to 2.7% caffeine by weight, while Arabica beans contain only 1.2 to 1.5%. That means a cup made from Robusta beans can have nearly double the caffeine of one made from Arabica. Most specialty and single-origin coffees use Arabica. Many cheaper blends, instant coffees, and some espresso blends include Robusta, which partly explains why a gas station cup can hit harder than a pour-over from a craft roaster.
Roast Level
There’s a persistent idea that dark roasts are “stronger” in caffeine. The opposite is closer to the truth. Roasting breaks down caffeine slightly, so dark roasts tend to be a bit lower in caffeine than light roasts. The difference is modest, though. Where it gets tricky is measurement: dark roast beans weigh less because they’ve lost more moisture, so if you scoop your coffee by volume (tablespoons), you’ll use more beans and end up with more caffeine. If you weigh your coffee, the light roast will come out slightly ahead.
Water Temperature and Contact Time
Hotter water extracts caffeine faster, but longer contact time can compensate for lower temperatures. Research on cold brew found that grind size had surprisingly little impact on final caffeine levels. What mattered more was how long the grounds sat in water. For hot brewing, the extraction happens quickly but is limited by how fast caffeine can diffuse out of larger particles. For cold brewing, the slower process eventually catches up or even surpasses hot extraction when given enough time.
How Chain Coffee Compares
Coffee from major chains tends to be stronger than what you’d brew at home with standard ratios. Chains often use a higher coffee-to-water ratio and brew at optimized temperatures for maximum extraction. If you’re buying a “tall” (12 oz) from a coffee shop, expect the caffeine to land on the higher end of the range, potentially 200 mg or more for a light-roast drip coffee.
The chain matters too. Different companies source different bean blends, roast to different levels, and use different brewing equipment. A 12 oz cup from one chain can easily contain 50 to 80 mg more caffeine than the same size from another.
What About Decaf?
Decaf isn’t caffeine-free. A 12 oz cup of decaf brewed coffee averages 7 to 8.4 mg of caffeine. Decaffeination typically removes about 97% of the caffeine, so a cup that would normally have 180 mg ends up with roughly 5 to 6 mg. Chain decaf varies: Dunkin’ decaf in a 10 to 12 oz serving contains about 7 mg, McDonald’s about 8 mg, and Starbucks’ Pike Place decaf comes in at 20 mg, notably higher than the rest.
If you’re sensitive to caffeine or limiting intake during pregnancy (the WHO recommends staying under 300 mg per day), those residual milligrams in decaf are worth tracking, especially if you’re drinking multiple cups.
Putting Your Daily Intake in Perspective
At 140 to 250 mg per 12 oz cup, most people can comfortably have two cups of drip coffee and stay well within the FDA’s 400 mg guideline. Three cups pushes you to the edge or over, depending on the brew. If you’re drinking percolated coffee, even two 12 oz servings could put you at 600 mg, well past the recommended limit.
Caffeine sensitivity varies widely from person to person, largely based on genetics and how quickly your liver processes it. Some people feel jittery after a single cup; others drink three with no noticeable effect. The 400 mg ceiling is a population-level guideline, not a personal prescription. If you notice disrupted sleep, a racing heart, or anxiety, your threshold is likely lower regardless of what the guidelines say.