We know it’s coming: that seemingly endless run of short drizzly days, repeated over and over again for months. Days where it never seems to get fully light, just an oppressive gray that, before you know it, is fading. You go to work in the dark and come home in the dark. How do we carry on? How do we get through the Pacific Northwest winters? Coffee.

Seems like you can’t walk a block without passing a coffee-buying opportunity, but what do you really know about your companionable, aromatic addiction? For starters, according to the Mayo Clinic, 400 mg. of caffeine is considered “safe” for most healthy adults. That translates into about four 12 oz. cups from McDonald’s. Or better yet, 18 oz. of Starbuck’s brewed coffee. Surprisingly, the darker the roast, the less caffeine, as it’s burned off in the roasting. A tall (12 oz.) blonde roast will average 270 mg. of caffeine as opposed to 195 mg. from a dark roast.

If you’re trying to cut back, order espresso over brewed. While an ounce of brewed coffee has 20 mg. and an ounce of espresso has 75 mg, a 12 oz. cup of brewed coffee will have 240 mg. of caffeine whereas a single shot Americano will have 150 mg.

Worried about dehydration from coffee? Don’t, it’s a myth. While there’s a slight diuretic effect, regular coffee-drinkers build up a tolerance and, overall, the amount of water in each cup easily offsets any risk of dehydration.

And just so you can cover most of your bases, here are the stats on some other favorites. Black tea? It takes six 12 oz. cups to get to 400 mg. of caffeine. Coca-Cola? You can drink up to twelve 12 oz. cans. Red Bull? Five 8 oz. cans.