The Scientific Reason Cream Keeps Your Coffee Hot For Longer

Depending on your priorities, how you take your coffee could depend on more than the flavor. And if you're someone who prefers to drink hot coffee leisurely, then it might be time to consider adding some cream. As it turns out, adding the extra ingredient to black coffee can keep it hot for longer. But why exactly does this happen? It all comes down to the naturally occurring properties of each liquid.

The first is that black coffee is a dark color, which means that it absorbs heat quickly. But the opposite physical reaction is also true. This means that the darker the coffee, the faster it will give off heat, too. So, when you add cream to a cup of black coffee, it will lighten its color and therefore cause it to cool off more slowly. This is also the reason that cold cream doesn't make your hot coffee cold. There is, however, another physical property of cream that is also effective at keeping your coffee hotter longer.

Unlike coffee, which is simply water that's been steeped with ground coffee beans, cream contains fat and water. And this is exactly why cream helps coffee retain heat — it adds viscosity. When your hot coffee has more viscosity, that simply means that the water evaporates slower, and therefore less heat is lost. While no one expects you to conduct physics experiments first thing in the morning, it's also helpful to know that the Stefan-Boltzmann Law explains that the hotter something is, the faster it will radiate its heat. So, in slightly lowering the temperature of coffee with cream, it will ultimately stay hotter for longer. 

Now that you fully understand the three reasons why cream keeps your coffee hotter for longer (lighter color, greater viscosity, cooler overall temperature), all that's left to do is have some fun adding different creamy inclusions. Use our ranking of 15 coffee creamer brands to experiment with flavors. Some people even add dry creamer to coffee grounds before brewing to tame bitterness and acidity! If you are a strict black coffee drinker, use these rules as a reminder to drink faster to enjoy it while it's hot. And it's still a good idea to order black coffee when trying out a new café to sample the brew's quality before masking its nuanced flavors with cream and sugar.