For coffee aficionados, seeking the perfect cup of coffee is something that is bound to spark interest. The answer to creating the perfect cup of espresso may lie in numbers and equations, according to a new study.

Through mathematics, scientists are seeking to overturn common espresso wisdom about the quantity of beans required to create a good cup of coffee. A researcher team have found that fewer coffee beans, when ground more coarsely, are the answer to a cup of coffee that is less expensive to produce, more consistent in quality from shot to shot, while remaining as intense as the espresso lover seeks. The coarseness counters the conventional wisdom of most coffee brewing processes.

One of the challenges associated with creating the perfect cup of coffee is that the mix of bitterness and sour acidity that is unpredictable and irreproducible. This relates to the fine grind settings being difficult to reproduce, together with variations relating to the number of coffee beans used.


The grind is an important determinant when it comes to brewing coffee. This is because the grind setting determines the particle size distribution of the coffee grounds (and therefore the surface area, which is key to flavor development).


According to mathematician Christopher Hendon, rather than trying to grind coffee finely and using lots of beans, his research team have experimentally shown: “efficient, reproducible shots can be accessed by simply using less coffee and grinding it more coarsely.”


This is because, grinding as finely actually lowers the extraction yield, wastes raw material, and adds a variation in taste. This is because the standard process used in many coffee shops only samples some grounds and missing others entirely, creating unpredictability in the coffee production process.



Cappuccino at Browns in London with the classic B marked in chocolate upon frothed milk.

Cappuccino at Browns in London, with the classic ‘B’ marked in chocolate upon frothed milk.
Tim Sandle



In demonstrating that coarse grinds produce better tasting coffee, the researchers have presented experimental measurements which demonstrate a peak in the extraction yield versus grind setting relationship. This shows inhomogeneous flow is operative at fine grind settings, resulting in poor reproducibility and wasted raw material. Whereas, with a coarser grind better coffee can be produced more consequently and fewer coffee beans are wasted.


As well as improving taste and consistency, the newly modeled process could create economic gains for coffee shops as well as helping to deliver sustainability benefits for the coffee industry.


The research has been published in the science journal Matter, with the research paper titled “Systematically Improving Espresso: Insights from Mathematical Modeling and Experiment.”