Coming out on top as the most jitter-inducing coffee on the market is Death Wish Coffee, (left), with a staggering 54.2 milligrams of caffeine in every fluid ounce of its Joe. Dunkin' Donuts (right) falls in the middle
By comparison, Starbucks has 20.6 milligrams of coffee per fluid ounce, followed by Caribou Coffee (15 milligrams), Dunkin' Donuts (12.7 milligrams), Seattle's Best (10.4 milligrams) and McDonald's (9.1 milligrams).
Higher caffeine levels generally correlate to higher prices. In New York, for example, the cost of a 12-ounce brewed coffee is $1.85 at Starbucks, $1.29 at Dunkin' Donuts and $1 at McDonald's.
Death Wish goes for about $19 for a pound of beans, which is twice as much as most regular coffee.
But the amount of caffeine in your coffee or tea will depend directly on how long you brew the beverage. When coffee grounds are in contact with water for a longer period of time, there will be more caffeine in your cup of Joe. When you steep a teabag for longer, your cup of tea will have a higher caffeine content.
The complexities don’t stop there. Dark roasted coffee beans are known to have a lower caffeine content than light roasted coffee beans as caffeine is lost in the roasting process. Arabica coffee beans also have a lower caffeine content than Robusta coffee beans.
In the world of tea, the color of a cup of tea does not indicate its caffeine content. A dark-colored tea may not necessarily have more caffeine than a light-colored tea. A light-colored cup of green tea often has more caffeine than darker tea blends.