By Mike Pomranz
Updated November 17, 2016
coffee roast, coffee
Credit: © Lisa Romerein/ Getty Images

In the olden days, the only math you used to make a cup of coffee was “How many tablespoons of Folgers do I dump in my Mr. Coffee?” But as our coffee drinking habits have become more refined, the math behind them needs to be more precise as well. It led a team of scientists to crunch the numbers on exactly how to make the perfect cup of joe. Sounds like we’re just a symposium on doughnuts away from finally nailing breakfast.

According to the University of Limerick in Ireland, where the research took place, the study, which was published this week in SIAM Journal on Applied Mathematics, looked at a “hideously complicated” group of variables despite narrowing its focus specifically to drip coffee. In the end, researchers determined that the size of coffee grains is the most crucial factor, though a laundry list of other elements certainly plays a role.

“From the shape of the filter, to the scale of a single grain, to the flow rate of water and which machine or tool is used, there are an enormous number of variables,” said Dr William Lee who co-authored the study. “But maths is a way of revealing hidden simplicity. By using mathematical analysis, we can begin to tell the story of which elements and in what order lead to the best coffee – we are now one step closer to the perfect cup of coffee.”

Lee delved deeper into the importance of grind size in a conversation with the BBC. “The really surprising thing to us is that there are really two processes by which coffee is extracted from grains,” he was quoted as saying. “There's a very quick process by which coffee's extracted from the surface of the grains. And then there's a slower tail-off where coffee comes out of the interior of the grains.” Because of this, Lee suggests a larger grind for a less bitter cup and a smaller grind if you like a bit more of a bitter bite.

Overall though, the team of mathematicians admit that, due to endless numbers of variables and the technical scope of their research, the results will be of the most interest to coffee machine manufactures who might be able to a tailor their brewers to work with a specific grind size to get a specific flavor profile. “For industrial applications, we'd hope you could optimise the coffee machine for a certain size of grains. You could adjust the flow rate so you get the perfect extraction there,” Lee said.

However, if you’ve been ignoring the grind size setting on your coffee bean grinder, math says you should give that a closer look.