It depends on what you had for your morning coffee:

If your morning cup came from a commercial roaster who included Robusta in the blend, we have another level of complexity. Caffeine content in these coffees, in one study, varied between 1.16 and 4.0%. A straight 12 oz. cup, using 20 grams of the 4% coffee, probably wouldn't taste very good, but would definitely provide more buzz: 800 milligrams of caffeine.

As with most things, the more one learns, the more complex a topic becomes and, in a sense, the less one knows. To attempt accurate generalization:

    • Arabica averages about half the caffeine as Robusta.
    • The cultivar determines the caffeine content.
    • Degree of roast has no meaningful effect on caffeine.
    • An espresso made from 100% Arabica, on average, has about 70 milligrams of caffeine per shot; a 12 oz. cup of drip coffee made my way in a press pot, using two scoops of coffee per 12-ounce cup -- would have 200 milligrams.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.