For a medium cup of coffee, which ranges from 12 to 16.8 fluid ounces (33.5 to 50 cl) at various coffee shop chains, you are going to get the most caffeine from Starbucks—330 milligrams of caffeine for its standard Pike Place roast, according to data from the companies and information compiled by the Center for Science in the Public Interest. But it will also cost you the most on average at about $2.
A $1.80 brew from Dunkin' Donuts has 178 milligrams of caffeine. At McDonald's, the typical $1 cup of joe packs 133 milligrams while Panera Bread's coffee costs about $2 and has 189 milligrams.
The convenience store chain Cumberland Farms offers a 99-cent coffee that has 220 milligrams of caffeine. The chain also offers a free caffeine booster with another 40 milligrams along with other condiments.
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If you make your coffee at home, you have control over the caffeine content as well as the price. Depending on the amount of coffee used and the brand, a 12-ounce cup brewed at home could run you as little as about a dime and deliver 150 milligrams or more of caffeine. Expect to pay at least twice that for a premium brand's bean.
Keurig Green Mountain, which makes single-serve brewing systems, says caffeine content in a single K-cup can range from 75 to 150 milligrams for an eight-ounce cup of coffee. While K-cup prices vary significantly by brand and size of package, a price of about 50 cents per serving is representative of what is available in U.S. grocery stores.
While instant coffee is hardly on anyone's best taste list, it is cheap—also in the neighborhood of a dime a cup—and can pack some serious caffeine, with 148 milligrams in a serving of Folgers Instant, a product of the J M Smucker, for example.