Cone vs Flat: How Coffee Filter Shapes Affect Your Brew

You already know that your choice of coffee beans, grind size, and brewing method affect the flavor of your coffee. But what about something as basic as the coffee filter shape? Does it have an impact?

Coffee nerds have long been debating this topic, and now we have an answer! So what have we learned about filter basket shapes, and how can we use it to brew better coffee? Keep reading to find out.

Does shape matter, and why?

If you’re a coffee-lover, you already know that drip coffee machines and some other coffee brewer types, like pour-over, have two types of filter baskets. There are cone filters and flat-bottom basket filters.

But have you ever wondered about the difference between the two? Well, some coffee scientists have, and what they learned is fascinating.

Specialty Coffee Association of America, the SCAA, ran the study. They found that even inexperienced tasters noticed different coffees brewed with different filter baskets (1). Says professor William Ristenpart, director of the UC Davis Coffee Center:

In fact, the only factor that tasters found even more impactful than basket shape was roast level (2). This comes as no surprise.

So why does basket shape make such a difference? It’s all about water flow. The basket’s shape impacts how the water flows through the ground coffee and thus how the coffee is extracted.

What is the difference?

The result of the different extraction in the different shaped baskets can be quantified using a measurement known as Total Dissolved Solids (TDS). Without getting too technical, TDS measures the degree of extraction. A higher TDS means the coffee is more fully extracted. It is essentially the amount of coffee in your coffee.

It has been found that flat bottom baskets produce coffee with lower TDS than cone filters, all other factors (like pouring technique, water temperature, and grind size) being equal.

How does it affect your brew?

This is what you really came here for, right? Now that we know all this, how can we use it to brew better coffee?

Generally speaking, the lower TDS from the flat baskets favours sweeter notes like fruits, honey, tea, and florals. The higher TDS from the cone filter baskets is better for bringing out darker and earthier flavours like umami, smoke, cocoa, and dried fruit.

For a detailed comparison, check out this video:

That said, there are many ways to influence the flavour of your coffee aside from basket shape. By far, the biggest factor is the type of coffee beans you buy. Varietal, origin, and roast level all play a huge role. Then you can also play with grind size and pouring technique.

The Verdict

There is no right or wrong filter basket shape. One doesn’t brew better coffee than the other. But now we know for sure that there is a difference. If you love smokey and earthy flavours, consider a conical basket. But if you prefer sweet and fruity flavours, opt for the flat basket.