Coffee 101: The Basics

Arabica grows at higher altitudes, tastes sweeter and more complex, and has less caffeine — usually 0.8–1.4% by weight. Robusta grows at lower altitudes, is more disease-resistant, and packs more caffeine — typically 1.7–4%. Arabica dominates specialty coffee; Robusta shows up in espresso blends (for crema and body) and most instant coffee.

An 8-ounce cup of brewed coffee has about 96 mg of caffeine on average, per Mayo Clinic’s numbers — though it can range from roughly 95 to 200 mg depending on the bean, grind, and brew method. A 1-ounce espresso shot has about 63 mg. If you’re tracking intake, the FDA-cited safe ceiling for most healthy adults is around 400 mg a day — roughly four 8-ounce cups.

No — this is one of the most common coffee myths out there. Caffeine barely changes during roasting. If anything, light roast beans are slightly denser, so by weight they can have marginally more caffeine than the same weight of dark roast. The “kick” people associate with dark roast is about bold flavor, not caffeine content.

Not entirely, but close. Per Mayo Clinic’s figures, an 8-ounce cup of brewed decaf has about 1 mg of caffeine, compared to 96 mg in regular brewed coffee — so it’s over 98% removed, not 100%. If you’re fully caffeine-avoidant for medical reasons, that small remaining amount is worth knowing about.

Somewhere between 195°F and 205°F (roughly 90–96°C) for almost every hot brew method — drip, pour-over, French press, and more. Water that’s too cool under-extracts and tastes flat or sour; water that’s too hot over-extracts and tastes bitter or burnt. If you don’t have a thermometer, boil your water and let it sit for 30–45 seconds before pouring.

Whole beans are best within about 2 to 4 weeks of their roast date. Ground coffee starts losing flavor within 1 to 2 weeks, since grinding exposes far more surface area to oxygen. Old coffee won’t hurt you — it just tastes flatter and duller the longer it sits, so buy only what you’ll realistically drink in a couple of weeks.