5 Levels of Coffee Bean Grind: What Grind Size for Pour-Over, Cold Brew, and Espresso?

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Regardless of the brewing method used, coffee beans must be ground. The purpose of this is to allow the flavor compounds in coffee to dissolve more quickly. Of course, not all soluble substances in coffee are delicious. Therefore, to maximize the extraction of desirable flavor compounds while avoiding undesirable ones, determining the appropriate coffee particle size becomes extremely important.

Different Coffee Brewing Methods Require Different Grind Sizes

Different coffee brewing methods require varying grind sizes due to differences in their extraction methods. Taking the most commonly encountered methods in our daily lives as examples: pour-over coffee, French press, espresso machine, and cold brew/drip coffee. The coffee grind sizes used by these methods, from coarsest to finest, are ranked as follows: [French press > pour-over coffee > cold brew/drip coffee > espresso machine].

While we understand which extraction methods require coarser grinds and which require finer grinds, we cannot determine precise numerical values. That is, exactly how coarse is "coarser," how fine is "finer," and what is this "relative comparison" based on?

Reliable Reference Standards

Although different coffee establishments have their own unique brewing standards, there is one standard recognized throughout the coffee industry: cupping! The original purpose of cupping was to inspect the quality of green coffee beans, so this method certainly contains valuable extraction principles. The coffee grind size for cupping is 70-75% pass-through rate through a #20 sieve.

Knowledge Note: A #20 Chinese standard sieve has an aperture of 0.85mm and is used as a tool for particle size classification and detection. Any standard sieve that meets factory standards is accurate. Coffee grinding calibration is also very simple: just pour the ground coffee into the sieve, cover it, shake it horizontally until no more particles fall through, and then weigh the particles that passed through. This way, you can determine the grind size. For example, if you grind 20g of coffee grounds and 15.2g pass through, then this grind size has a 76% pass-through rate through the #20 sieve. The higher the pass-through rate, the finer the coffee grind.

Since cupping can be calibrated using standard sieves to determine grind size, the grind sizes corresponding to the coffee brewing methods we commonly use can also be clearly listed with data.

French Press (68-75% pass-through rate through #20 sieve)

The extraction method of French press is very similar to cupping, as both are primarily based on immersion. Therefore, the chosen grind size highly overlaps with cupping. There's another reason for choosing coarser grind particles: because French press filtration uses a metal filter with visible gaps to the naked eye, choosing a coarser grind also facilitates better filtration. Different roast levels of coffee beans also require different grind sizes. Light to medium roast coffee beans can use a slightly finer grind (72-75% pass-through rate), while medium to dark roast coffee beans can be ground coarser (68-71% pass-through rate).

Pour-Over Coffee (70-80% pass-through rate through #20 sieve)

Pour-over coffee is primarily based on drip filtration. Unlike immersion methods, which have longer extraction times and can easily extract undesirable flavors, pour-over coffee has a shorter brewing time, approximately 1 minute 30 seconds to 2 minutes 30 seconds. Therefore, a finer grind than cupping is needed to fully express the coffee's flavors. Similarly, different roast levels of coffee beans require different grind sizes. Light to medium roast coffee should be ground finer (75-80% pass-through rate), while medium to dark roast coffee beans can be ground coarser (70-75% pass-through rate).

Cold Brew/Drip Coffee (80-85% pass-through rate through #20 sieve)

Cold brew and drip coffee both use cold water for extraction, which has poor penetration capabilities and very low extraction efficiency. Therefore, the coffee needs to be ground finer. However, remember that finer is not always better. Excessively fine grinding can make cold brew coffee cloudy and increase filtration difficulty; for drip coffee, it can cause water accumulation in the coffee bed, preventing smooth passage. Therefore, a grind size with an 80-85% pass-through rate through the #20 sieve is more appropriate. If you want a richer flavor, choose 85% pass-through rate; if you prefer a cleaner taste, choose 80% pass-through rate.

Note: Due to differences in coffee bean density and roast levels, even if you grind two coffee beans with significantly different densities using the same grinder at the same setting, their resulting particle sizes may not be the same. For example, when grinding FrontStreet Coffee's Yirgacheffe coffee beans using an EK-43s at setting 10, the corresponding sieve pass-through rate is 80%, while grinding Colombian Rose Valley at the same setting 10 results in a 75% pass-through rate. Therefore, when you feel the grind size is not quite right, it's best to confirm the grind size using the same type of beans.

Espresso Machine

The grind size used for espresso machines is very fine, and using sieves to screen is not practical. The primary way to determine the appropriate grind size for espresso is through extraction testing. Coffee shops need to calibrate their espresso before daily operations, and a significant part of this process involves adjusting the grind size. Because espresso machines are very sensitive to coffee grind size, even a difference of 0.1 on the grind setting can result in noticeable differences in extraction time and flavor.

Therefore, determining the grind size for an espresso machine requires a stable espresso extraction recipe. Taking FrontStreet Coffee's recipe as an example: FrontStreet Coffee's espresso recipe is 20g of coffee grounds to extract 40g of coffee liquid in 28 seconds (with a margin of error of ±1). First, this extraction recipe is fixed, and then the grind size is adjusted to achieve this recipe. Afterward, taste testing determines whether parameters need fine-tuning.

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