From Coarse to Fine: Exploring the Impact of Grind Size on Cold Brew Coffee

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One of the more important variables in brewing cold brew coffee is grind size. Before we start looking at the differences in grind sizes, it’s important to understand why size matters when brewing coffee.

The Role of Grind Size in Cold Brew Extraction

Cold brew coffee is made by soaking coarsely ground coffee beans in cold water for a long time, usually overnight. This slow process helps to gently extract the flavors, resulting in a smooth and less acidic coffee.

Unlike hot brewed coffee, which uses hot water for quick flavor extraction, cold brew uses cold or room temperature water for several hours to make coffee.

To make up for the longer extraction time needed with cooler water, we reduce the amount of coffee’s surface area in contact with the water. The larger particles of a coarse grind allow for a slower extraction process, resulting in a milder and less acidic brew.

Using a fine grind size for cold brew can lead to over-extraction, where the flavors become overly bitter and intense. The smaller particles of a fine grind release more compounds quickly, resulting in an unpleasant taste.

It can seem counter-intuitive to think that a larger grind size has less surface area, but I promise if you do the math there is more surface area on grains of sand than a similar amount of pebbles.

The Relationship of Grind Size to Time

If you buy a bag of ground coffee from the grocery store, chances are it is medium grind. As you can see from the table below, a lot of common brewing methods use something in the range of medium grind, including drip coffee.

Brewing Method	Grind Size	Micron Range
Turkish Coffee	Extra-fine, like flour	40-220 microns
Espresso	Fine, similar to table salt	180-380 microns
AeroPress	Medium-fine to coarse	N/A
Moka Pot	Medium-fine, gritty texture	360-660 microns
Pour Over (e.g., Chemex, V60)	Medium to medium-coarse, like sand	410-930 microns
Drip Coffee Machine	Medium, like sand	N/A
French Press	Coarse, like sea salt	690-1300 microns
Cold Brew	Extra-coarse, like ground peppercorns	820-1270 microns

If you can only find ground coffee, or if you don’t own a grinder, you can absolutely use medium ground coffee. You just want to adjust your brew time to be shorter. I recommend 10-14 hours.

How to Get Coarsely Ground Coffee Beans

1. Grind it yourself

For the perfect grind size for cold brew coffee, use a conical burr grinder. This type of grinder allows precise control over the grind size, ensuring your coffee grounds are consistent and uniform.

A burr grinder crushes the coffee beans between two abrasive surfaces, resulting in a more uniform grind size compared to blade grinders.

Blade grinders tend to result in a range of particle sizes. This means you can end up with a mix of particle sizes, some of which will under-extract and some of which will over-extract.

The consistency you are looking for has been compared to coarse salt, breadcrumbs, or ground peppercorns.

While a burr grinder is an investment, there are some great modestly priced options. I personally have been using the Cuisinart DBM-8 (affiliate link, Amazon) for several years now. It has 18 grind settings from fine to coarse. This works well in our household where one of us drinks only cold brew, and the other makes espresso daily.

2. Buy Coarse Ground Beans

With the popularity of cold brew coffee, you can now buy beans already ground for use in cold brew. While I rarely see these in the supermarket, they are easily found online.

If you are interested in some recommendations, I wrote more about the best beans for cold brew here.

So, we have learned that size really does matter. If you want to know more about the other variables in cold brewing, you can learn more here: