Does roasting destroy caffeine?

The belief that roasting destroys caffeine is one of the most persistent myths in coffee science. In reality, caffeine is remarkably thermostable, with a melting point of approximately 455°F (235°C)—well above the typical temperatures reached during the roasting process, which usually peak between 380°F and 430°F. Scientific studies confirm that caffeine degradation during roasting is minimal, often cited as less than 5-10% even under severe roasting conditions.

So, why does the confusion persist? The answer lies in the physical transformation of the coffee bean. As green coffee is roasted, it loses moisture and organic matter, causing the bean to lose mass and expand in volume. A dark-roasted bean is less dense and larger than a light-roasted bean. If you measure your coffee by volume—such as using a scoop—a scoop of light roast will contain more individual beans (and thus more caffeine) than a scoop of dark roast because the light beans are denser.

However, if you measure your coffee by weight, which is the standard practice in specialty coffee, the caffeine content remains nearly identical regardless of the roast level. Gram for gram, a light roast and a dark roast provide almost the same amount of caffeine. The 'strength' people associate with dark roasts is a result of flavor development, such as caramelization and the creation of bitter compounds, rather than a higher concentration of stimulants.

In practice, this means you should choose your roast level based on your flavor preference rather than your caffeine needs. If you are looking for a specific caffeine kick, the most significant variables are the coffee species—Robusta contains roughly twice the caffeine of Arabica—and the total amount of coffee used in your brew. Whether you prefer a light, medium, or dark roast, the caffeine content will be effectively the same.