What's The Best Grind Size For Cold Brew Coffee?

Author: Melissa Collins

Updated: October 20, 2022

Cold brew is a unique type of coffee that is frequently misunderstood as simply being iced coffee like that sold in Starbucks and other major coffee shop chains.

Cold brew is certainly a coffee you can drink ice cold, but that doesn’t define it. Instead, cold brewed coffee is defined by the method of using room temperature or cold water to extract flavor from the beans rather than using hot water.

It takes anywhere from a few hours to a whole day to complete the process. But, it creates some exciting results.

In today’s guide, we’re looking at what size you should grind your coffee beans to when making cold brew coffee.

Coffee Grind Sizes: An Overview

If you’ve never done your own coffee bean grinding before, you might wonder what we’re referring to when we talk about different coffee grind sizes. The fact is that how you grind the beans ultimately has a lot of impact on the overall flavor of your coffee because how you grind affects extraction.

Grind sizes are measured in a scale of levels 1-10, 1 being the finest most powder-like grind, and 10 being the coarsest grind. The finer the grind, the more flavor you will extract within the time you’re brewing the coffee.

If you grind the beans too fine for your usual brew, it will over-extract the coffee and become bitter and unpleasant to drink. If you under-extract, it will be weak and flavorless. You have to strike the right balance.

Different Coffee Grind Sizes Compared

So, how do these different coffee grind sizes compare to each other? We’ve split them up into three categories: Fine, Medium and Coarse.

Fine Grind (Level/Setting 1-3)

Fine grinds are used when the coffee you are making is only to be exposed to the hot water element for a very short time, such as mocha or espresso coffees that you find in many popular franchised outlets and independent coffee shops.

Level 1 can be used for mocha, and levels 2-4 for both espresso and in automatic coffee dispensers like those you might find in a hospital. Contact between the water and the coffee will be short, so all the flavor needed has to be extracted quickly.

Medium Grind (Level/Setting 4-6)

These levels of grind suit a wide range of different coffee-making apparatus, including filter coffee machines that people very often use at home. It’s a happy mid-level grind that can please the great bulk of the coffee drinking masses with relatively few exceptions. When you’re making fresh coffee and grinding the beans yourself for the first time, a medium grind level 4-5 is a great place to start.

Coarse Grind (Level/Setting 7-10)

In a coarse grind, the grounds created are noticeably larger than either fine or medium grind levels. This is conducive to coffee brewing processes where the coffee grounds and the water remain in contact for long periods of time, even the entire day.

When you’re using a French press, a Karlsbad coffee maker or a vacuum coffee maker, coarse grounds are best, between levels 6-9.

As it happens, a coarse grind of level 10 is about what you need for a successful cold brew. That brings us neatly to the next section of the blog.

Choosing the Right Size

Even though there are many important factors that make the “right” coffee bean for a cold brew, many baristas would argue that the grind is the most important of them all.

It’s not to say that other factors such as the bean variety, location and elevation of growth, picking method, and the roasting method are unimportant, but just that the grind size really matters that much more.

No matter how much care you take to get the right kind of beans for your cold brew, if you mess up the grind, it won’t work. The cold brew needs the coarsest among the generally accepted levels and settings for coarseness that your grinding apparatus allows. The final consistency should be quite gritty, almost like picking up a handful of beach sand and rubbing it between your fingers.

With a coarse grind, the water flows around each part faster and more easily. When the grind is too fine, the extraction happens much faster and the result is a bitter and very unpleasant taste.

Remember that the water and the coffee are going to be together for a long period of time, so the coffee grounds and water need to move freely to allow slow, mild and steady extraction of the best flavors.

Why Not Buy Pre-Ground Coffee?

The simple answer to this is that pre-ground coffee cannot, by definition, be as fresh as the beans you grind yourself. When they have been ground before, they are already losing their freshness as they make contact with oxygen, which is diminishing their intense flavors and aromas.

No matter how well the coffee is sealed and kept, it’ll just not be the same as fresh-ground coffee.

Why You Should Grind Your Own Coffee Beans

If you are someone who cares about the intricate and complex flavors of coffee, then you should always grind your own coffee beans. When beans are left whole, they retain these flavors much more effectively than they would do when they are ground.

It’s not dissimilar to what happens when you cut up fruit ahead of eating instead of leaving it whole until it’s time to eat. After it’s cut, oxidation begins and the fruit loses its juices and natural appeal. The same is true of pre-ground coffee.

When you grind it yourself, you unleash those fantastic taste profiles, but you also get to enjoy it immediately. Just think of the time gap between coffee that’s roasted somewhere far away, packaged, shipped, stored and then sat on a shelf waiting for you to buy it. Grinding the beans yourself is really the only way to guarantee that you’ll get everything from your coffee that you desire.

Summing Up: Making Cold Brew? The Coarser the Better

At the core of our blog today is the best grind size for cold brew coffee. The answer is that the coarser the grind, the better.

If you’re using a grinder or coffee machine with a built-in bean grinder, set the coarseness level to maximum, which is usually level/setting 10.

Remember that the best cold brew doesn’t have to be made with ice water, and that the contact between bean and water can be as long as 24 hours to get the results you want.

Take care of the grind size, and the grounds you make will help you take care of the rest.