What is the difference between light roast and dark roast caffeine content per shot?

When pulling an espresso shot, the caffeine content is determined by the mass of the coffee grounds used and the extraction efficiency, not the roast color. Because caffeine is heat-stable, the roasting process does not 'burn off' the caffeine. Instead, the roasting process changes the physical structure of the bean, causing it to lose mass and expand.

In a professional cafe setting, baristas typically use a scale to dose espresso by weight. When you use 18 grams of light roast and 18 grams of dark roast, you are using the same amount of raw material. Since the caffeine content per gram of coffee is nearly identical across roast levels, the resulting shot will have a nearly identical caffeine profile.

If you were to dose by volume—such as filling a portafilter basket to the brim without a scale—you would likely use less mass with a dark roast because the beans are larger and less dense. In that specific scenario, the dark roast shot would contain slightly less caffeine. However, this is a result of the measurement method, not the roast itself.

For the espresso enthusiast, this means you should choose your roast based on the flavor profile you prefer rather than perceived caffeine strength. Whether you enjoy the bright, acidic notes of a light roast or the deep, chocolatey body of a dark roast, your caffeine intake will remain consistent as long as your dosing remains precise. Focus on your grind size and extraction time to dial in the perfect shot.