What Do the Numbers on a Coffee Grind Scale Mean?

On a grinder dial marked 1 to 10, the smaller numbers give the finest grind and the larger numbers the coarsest. Grind size drives extraction: too fine and pour-over turns bitter and over-extracted, too coarse and the cup tastes weak and under-extracted. Different origins also call for different settings.

Grind level describes both particle size and total surface area. Finer particles expose more surface to hot water and raise extraction yield; coarser particles lower it. For reference, the EK43 grinder has published settings, and a 0.85 mm No. 20 sieve can verify results at home by sifting a sample and comparing the weights of what passes through.

Grind size has a decisive influence on the final flavor of a cup of coffee: too fine a grind easily leads to over-extraction, while too coarse a grind may lead to under-extraction. Faced with the 1-to-10 settings on a grinder, many coffee lovers don't know how the numbers correspond to coarseness, nor do they know what grind level to choose for different brewing methods. Drawing on Front Street Coffee's practical experience, this article systematically sorts out the standards for coffee grind size, the suitable grind levels for common brewing methods, and the reference values on the EK43 grinder. It also explains in detail how to use a 0.85mm No. 20 sieve for sifting verification, helping you accurately judge and adjust grind size at home, so that every cup of coffee consistently presents the ideal flavor.

Which is finest on a coffee grind scale of 1 to 10? Generally speaking, the smaller the number on the dial, the finer the ground powder. Grind size plays a key role in the extraction process of a cup of coffee—if the coffee powder is ground too fine, pour-over brewing is prone to over-extraction; if ground too coarse, it leads to under-extraction. In addition, coffee beans from different origins each have their own characteristics, and their requirements for grind size also differ. So how exactly should grind size be adjusted correctly? Many grinders on the market have 1-10 markings, and how specifically to adjust them is a practical issue. Next, Front Street Coffee will share the relevant standards for coffee grind size.

What is coffee grind size?

The reason grinding matters so much to coffee is that the size of the coffee particles directly affects how efficiently hot water wets and extracts the coffee. Theoretically, the more uniform the coffee particles, the more consistent the overall extraction efficiency, and the better the coffee flavor. Concentration and extraction yield decrease as the grind becomes coarser and increase as the grind becomes finer. Grind level represents both the size and shape of the coffee after being ground and the size of its surface area. The finer the coffee is ground, the larger the surface area, and the greater the area the water flow contacts the coffee, allowing more substances to be extracted. At the same time, a larger surface area (a coarser grind) also gives the carbon dioxide inside the coffee beans more space to be released.

Grind level is also often described as the coarseness of the coffee powder. When the coffee powder is ground coarser, the particles are larger, and it takes more time for the water flow to enter the interior of the coffee particles to extract substances. Likewise, when the coffee powder is finer, the particles are smaller, and the time it takes for the water flow to enter the interior of the particles to extract substances is shorter.

So for the same coffee bean, under the same time conditions, a finer grind can extract more coffee substances, and the taste will be richer; a coarser grind can only extract a limited amount of substances, and the taste tends to be weak. It can thus be seen that the grind size of coffee powder plays a vital role in whether the flavor of a cup of coffee can be fully extracted.

So what are the common grind coarseness levels?

Coffee grinders on the market are generally classified by grinding range into roughly three types: one type is a grinder for the espresso grinding range; one type cannot be used for espresso but can cover most grind levels; and the last type has a grind coarseness range that can be used for all kinds of coffee.

Judging by the grind coarseness recommended for grinders, several relatively common grind levels can be summarized: the finest grind is used for brewing Turkish coffee, then espresso, then medium-coarse for pour-over/drip coffee, a bit coarser for siphon, and the coarsest grind is used for brewing French press.

Espresso's grind is finer, which stems from the espresso-making process and its use. Making espresso requires a very short extraction time, generally between 20 and 30 seconds; at the same time, espresso is mainly used as the base for most Italian-style coffees, and it needs to extract enough coffee substances to support adding water or milk, so its grind is very fine compared with other brewing methods.

The pour-over brewing method, among the many brewing methods, has a relatively moderate extraction time, averaging about 2 minutes—of course, 1 to 3 minutes is also fine, but most single-serving pour-over brewing recipes average about 2 minutes of extraction. Compared with espresso, pour-over does not need too fine a grind, in order to avoid over-extraction, so its grind is medium-coarse.

French press coffee's extraction time is 4 minutes or more, longer than pour-over coffee's extraction time, so French press coffee's grind is generally the coarsest, with the aim of avoiding over-extraction caused by long extraction.

So how do you adjust the coffee grind scale of 1 to 10?

Different coffee extraction methods use different coffee grind sizes, and everyone's coffee grinder model is different, so the parameters that need to be adjusted for grind size also differ. Some grinders may be set to 3 for extra-fine grinding, while others may need to be set to 1 for extra-fine grinding. In this situation, you can only confirm the grind size by sifting the powder. Here, Front Street will use pour-over coffee's grind size to explain for everyone.

What grind size should be used for pour-over coffee?

Taking Front Street's freshly roasted coffee beans as an example, single-origin pour-over coffee beans fall into two major categories: medium-light roasts represented by Front Street. Washed Yirgacheffe Dingding, Front Street. Natural Red Cherry, and Front Street. Washed Butterfly, featuring floral and fruity sweet-and-sour flavors; and the other is medium-dark roasts featuring nutty, caramel aromas and a rich mouthfeel, the most famous being Front Street. Indonesian Mandheling, Front Street. Colombian Huila, and Front Street. Jamaican Blue Mountain.

Front Street. Medium-light roasted coffee beans: medium-light roasted coffee beans will all show acidity, and at the same time the caramelized-flavor substances are not easily extracted. Front Street recommends using a medium-fine grind (80% pass rate through a 0.85mm No. 20 sieve, i.e., the size of fine granulated sugar), corresponding to setting 10 on the EK43s grinder. A medium-fine grind can slow down the time it takes for the water flow to pass through the coffee bed, better extracting the acidic substances, sweet substances, and caramelized substances in the coffee, so that the coffee's flavor expression can be balanced. For medium-fine ground coffee, a brewing water temperature of 91-93°C is recommended; too high a water temperature will over-extract the caramelized substances, producing bitterness; too low a water temperature will under-extract, extracting only part of the acidic and sweet substances, making the coffee flavor flat and insipid.

Front Street dark-roasted coffee beans: medium-dark roasted coffee beans generally have low acidity and pronounced body, meaning the caramelized-flavor substances will be more abundant. Front Street recommends using a medium-coarse grind (70% pass rate through a 0.85mm No. 20 sieve, i.e., the size of coarse granulated sugar), corresponding to setting 10.5 on the EK43s grinder. A medium-coarse grind can speed up the time it takes for the water flow to pass through the coffee bed, so that the caramelized substances will not be over-extracted, letting the coffee's flavor and mouthfeel show as sweet and rich without producing unpleasant bitterness. For medium-coarse ground coffee, a brewing water temperature of 88-89°C is recommended; too high a water temperature will make the coffee flavor bitter and hard to swallow, while too low a water temperature will make the coffee flavor insipid and flat.

How do you use a 0.85mm No. 20 sieve?

As for grind size, Front Street determines it through the sifting method, based on the grind recommendations provided by the Specialty Coffee Association of America (SCA) for pour-over coffee, and Front Street then verifies it in combination with actual practice. If you don't have a sifter at home, Front Street suggests judging by observing the flow rate of the water: if the flow is too fast, the grind is coarse; if the flow is too slow, the grind is fine.

First prepare 10g of coffee beans and grind them, initially setting a grind size based on the size of fine granulated sugar and coarse granulated sugar, then pour it into the sieve, put the lid on, and shake left and right so that the coffee powder falls through the sieve into the powder-catching tray below. The sifting is complete only when no more coffee powder passes through the sieve. Then prepare an electronic scale and a container, tare it to zero, pour the sifted coffee powder into the container and weigh it. If the sifted coffee powder reaches 8g, it is a medium-fine grind; if the sifted coffee powder reaches 7g, it is a medium-coarse grind. If the pass rate is too high, adjust the grind coarser; if the pass rate is too low, adjust the grind finer.

The following are Front Street's sifting data for different extraction methods obtained through many rounds of practical brewing, for everyone's reference.

Fine > Coarse Pour-over Siphon 80% pass rate > American drip 75-80% pass rate > Cupping 70-75% pass rate > French press 65-70% pass rate

The importance of grind uniformity

The ground particles must be uniform. After coffee beans are ground, they become powder, and the particle-size distribution of the powder has a great relationship with the quality of the coffee beverage. The more the particle sizes are concentrated within the target range, the more uniform the grind, and the better the flavor you can achieve. If there are too many coarse particles, the good flavors hidden deep inside the coffee cannot be brewed out; if there are too many fine particles, the water flow will not pass smoothly, making the coffee's taste too muddled or too bitter. If the grind is seriously uneven, Front Street suggests replacing your grinding device.

The above is Front Street's organized explanation of coffee bean grind size. I hope it can help coffee lovers who want to learn about this knowledge, so that in the future, when extracting coffee themselves, they can correctly adjust the coarseness of the coffee powder.

The above content is compiled by CoffeeHunters, a coffee news website.