When it comes to enjoying a cold beer, every detail counts, even the shape of the glass. A scientist at the Federal University of São João del-Rei in Brazil has taken on an unusual but relatable challenge: identifying the most effective beer glass design to keep drinks cold longer, without relying on insulating materials.

The new study reveals an optimal shape that minimizes heat transfer, enhancing beer drinkability in everyday settings.

Turning a Beer Glass into Math

The study’s author, Claudio C. Pellegrini, used mathematical principles to address a surprisingly complex problem. The researcher modeled the glass as a “body of revolution,” a necessary simplification that allowed him to focus on the relationship between heat transfer and the glass’s geometry.

The goal was to minimize heat entering the liquid from the environment, thereby keeping the beer cold for a longer time. To solve the problem, Pellegrini turned to an optimization technique commonly applied in physics and engineering. He based his calculations on the first law of thermodynamics, seeking to design a glass that slows heat transfer by optimizing the ratio between the glass’s surface area and volume. As the drink is consumed, both the shape of the glass and the exposed surface area change. Heat transfer varies depending on the amount of beer left in the glass, so this dynamic was an important challenge.

The implications go beyond the science of beer. Geometry optimization is widely applied in engineering and biology. From optimizing fuel efficiency in vehicles to enhancing the cooling of electronics, surface-area-to-volume ratios are crucial.

Shaping the Ideal Beer Glass

Pellegrini discovered that the best glass shape should be narrow at the base and gradually widen toward the opening. This design effectively reduces the surface area exposed to the air and slows the rate of heat entering the beer from the environment. Unlike traditional pint glasses with straight sides, which quickly expose a larger surface area, the optimized shape maintains a slower warming process as the beer is consumed.

This design might sound familiar because it’s a feature of some traditional beer glasses, such as the Brazilian tulip, the imperial pint, and the Weizenbeer glass, all of which widen near the top. For Pellegrini, this is no coincidence; these shapes have likely evolved, consciously or unconsciously, to minimize heat transfer while balancing the drinker’s experience.

The optimal design was tested against existing popular glass shapes. By comparing mathematical models, the researchers found that a narrow-to-wide configuration consistently performed better than straight-sided designs, reducing the beer’s warming rate across different drinking environments.

What about foam? Indeed, traditionally, beer enthusiasts have used foam to limit heat transfer, as foam acts as a thermal insulator and prevents carbon dioxide from escaping. While effective, foam dissipates over time, especially in hot weather.

So, what’s the worst?

As for the worst beer glass, Pellegrini is unreserved.

“The American glass, also known as the “Nadir Figueiredo glass”, due to the family name of the first industry to manufacture it, contains a rather low volume (190 ml) and is exceptionally ugly. Still, it is the most widely used beer glass in Brazil, counting more than 6 billion units manufactured since its introduction in the 40s. It is considered an icon in beer drinking and costs less than a quarter dollar. It maintains the beer cold through the most primitive of the processes: due to its low capacity, the beer is consumed so quickly it has no time to get warm,” he wrote in his study.

The findings were posted in Physics Arxiv.