The Absolute Best Grind Size For Cold Brew Coffee

Cold brew coffee seems to be having a moment — a moment, that is, that started about a decade ago, when so-called Third Wave coffee shops, including Stumptown Coffee Roasters and Blue Bottle Coffee, began offering, respectively, their popular Nitro Cold Brew and New Orleans Style Iced Coffee (via Bean & Bean Coffee Roasters). Coffee drinkers really took to this style of coffee, which is slow-brewed in cool water for 12-24 hours, noting its less-bitter flavor profile, its super-high caffeine content, its low acidity, and its versatility (via Coffee Bear). Coffee giants such as Starbucks and Dunkin' were a bit slower to pick up on the cold brew trend, introducing their versions, respectively, in 2015 and 2016, but after that, the cold brew juggernaut could not be stopped, with the value of the U.S. market estimated to be about $166 million in 2017, and projected to reach $944 million by 2025 (via Statista).

Although cold brew is now easily snagged at almost any coffee shop around town, the great thing about it is that it's easy to make at home: All you need is coffee, water, and equipment that can be as simple as a fine-meshed strainer and some cheesecloth (via Kitchn). The most important detail to making great cold brew? The size of the grind of your coffee.

Have you ever thought about why different coffee making processes call for different sizes of ground coffee? According to MasterClass, that's because the more finely ground coffee is, the more exposed surface area it has, meaning that its flavor will be extracted faster. For example, espresso is ground very finely because the water that passes through the grounds to extract them rushes through very quickly, meaning that in order to adequately brew the coffee, it will have to come into contact with the beans' exposed surface area.

Cold brew, on the other hand, requires a much slower coffee brewing method, according to MasterClass. Whereas espresso can be brewed in 30 seconds and drip coffee takes about five minutes (via National Coffee Association), cold brew coffee grounds steep in cool water for up to 24 hours, according to Cold Brew Hub. In order for those grounds to steep slowly and avoid the production of any bitter flavors, it's important that they be extra-coarse, advises Kitchn — about the texture of raw sugar. If you're working with a small home grinder, the outlet writes, work in batches to avoid over-grinding the beans.