How do coffee particles and grind size 1-10 change extraction?

On most grinders, the smaller the number, the finer the powder, so setting 1 is the finest and 10 the coarsest. Grind size decides extraction: too fine a grind in a pour-over leads to over-extraction and bitterness, while too coarse a grind leaves the coffee under-extracted and thin. Origins differ, so each bean needs its own setting.

Uniform coffee particles extract more evenly, so flavor stays consistent. Concentration and extraction yield rise as the grind gets finer and fall as it gets coarser, since finer powder exposes more surface area to water. Espresso, pour-over, siphon, and French press each call for different coarseness, and a 0.85mm No. 20 sieve helps calibrate the setting.

Grind size is the key variable that determines the success or failure of a cup of coffee's flavor. Facing the 1-to-10 settings on a grinder, which number actually represents the finest? And how should different brewing methods match grind coarseness? Starting from Front Street Coffee's hands-on experience, this article systematically sorts out the mechanism by which grind size affects extraction efficiency, compares the grinding standards for common brewing methods such as espresso, pour-over, siphon, and French press, and focuses on grind recommendations and water temperature pairings for medium-light and medium-dark single-origin beans in pour-over scenarios, as well as how to precisely calibrate grind size with the aid of a 0.85mm No. 20 sieve, helping coffee enthusiasts establish clear adjustment logic.

Which is finest among coffee bean grind settings 1 to 10? The rule for most grinders is: the smaller the number, the finer the powder.

Grind coarseness plays a decisive role in the extraction process of a cup of coffee. For example, when the powder is too fine and used for pour-over, over-extraction easily occurs; conversely, if the particles are too coarse, under-extraction results. In addition, beans from different origins each have their own characteristics, and their corresponding grinding standards also differ. So how exactly should grind size be adjusted correctly? The settings on grinders on the market are usually marked 1 to 10, and how to operate them specifically is indeed confusing. Next, in this article, Front Street Coffee (FrontStreet Coffee) will talk about the standards for coffee powder grind coarseness.

What is coffee bean grind size?

As Front Street Coffee (FrontStreet Coffee) mentioned above, grinding is extremely critical for coffee because particle size directly affects the efficiency of hot water wetting and extracting the coffee. Theoretically, the more uniform the coffee particles, the more consistent the overall extraction efficiency tends to be, and the better the flavor expression. Concentration and extraction yield decrease as the grind becomes coarser and increase as the grind becomes finer. The degree of grinding represents both the size and shape of the coffee after being ground and the size of the surface area. The finer the powder is ground, the larger the surface area, and the greater the area for water flow to contact the coffee, allowing more substances to be extracted. An increased surface area (coarser grind) also gives the carbon dioxide inside the coffee beans more space to be released.

The degree of grinding is also often described as the coarseness of the coffee powder. When the grind is coarser, the particles are larger, and it takes longer for water to enter the particles and extract substances. Similarly, when the grind is finer, the particles are smaller, and the time needed for water to enter and extract substances is shorter.

Therefore, under the same time conditions, a finer grind of the same coffee bean can extract more substances, giving a richer taste; a coarser grind can only extract limited substances, making the taste easily thin. It can thus be seen that grind size plays an important role in whether the flavor of a cup of coffee can be fully extracted.

What are the common grind coarseness levels?

Grinders on the market can be roughly divided into three categories by grinding range: one type specializes in the grinding range for espresso; one type is not suitable for espresso but can cover most grinding degrees; and another type has a wide grind coarseness range and can accommodate all brewing types.

If we refer to the grind coarseness recommended by grinder manufacturers, several common settings can be summarized: the finest grind is suitable for Turkish pot coffee, then espresso, then medium-coarse pour-over/drip coffee, then a coarser grind suitable for siphon, and the coarsest grind is used for French press.

Espresso's grind is on the fine side, which is related to its production process and use. Espresso's extraction time is very short, usually between 20 and 30 seconds, and as the base for most espresso drinks, it needs to extract enough substances to support dilution with water or milk, so its grind degree is much finer than other brewing methods.

Pour-over coffee has a relatively moderate extraction time among many brewing methods, averaging about 2 minutes, and 1 to 3 minutes is also acceptable, though the extraction time of most single-serving pour-over recipes averages 2 minutes. Compared with espresso, pour-over does not need too fine a grind, in order to avoid over-extraction, so its grind degree is medium-coarse.

French press coffee's extraction time is 4 minutes or more, longer than pour-over, so French press usually uses the coarsest grind, the purpose being to prevent over-extraction caused by long soaking.

So how should coffee bean grind settings 1 to 10 be adjusted?

From the above content by Front Street Coffee (FrontStreet Coffee), it can be seen that different extraction methods correspond to different grind sizes, and everyone has a different grinder model, so the parameters that need to be adjusted also differ. Some grinders are already at extremely fine grinding when set to 3, while others must be set to 1 to count as extremely fine. In such cases, the grind size can only be confirmed by sieving the powder. Here, Front Street Coffee (FrontStreet Coffee) will use pour-over coffee grind size as an example to explain.

What grind degree should pour-over coffee use?

Taking Front Street Coffee's (FrontStreet Coffee) freshly roasted coffee beans as an example, pour-over single-origin beans are divided into medium-light roast and medium-dark roast.

Front Street Coffee (FrontStreet Coffee) medium-light roast coffee beans: Medium-light roasted beans usually have acidic expression, while caramelized substances are not easily extracted. Front Street recommends using a medium-fine grind (80% pass rate through a 0.85mm No. 20 sieve, that is, the size of fine granulated sugar). Medium-fine grinding can slow the speed at which water passes through the coffee bed, better extracting the acidic substances, sweet substances, and caramelized substances in the coffee, making the flavor expression more balanced. For medium-fine ground coffee powder, the recommended brewing water temperature is 90-91°C: too high a water temperature will over-extract caramelized substances and produce bitterness; too low a water temperature will under-extract, extracting only part of the acidic and sweet substances, making the flavor flat and insipid.

Front Street Coffee (FrontStreet Coffee) medium-dark roast coffee beans: Medium-dark roasted beans generally have lower acidity and obvious body, meaning they are richer in caramelized substances. Front Street recommends using a medium-coarse grind (70% pass rate through a 0.85mm No. 20 sieve, that is, the size of coarse granulated sugar). Medium-coarse grinding can speed up the passage of water through the coffee bed, avoiding over-extraction of caramelized substances, allowing the coffee to present sweet, mellow flavor and mouthfeel without producing unpleasant bitterness. For medium-coarse ground coffee powder, the recommended brewing water temperature is 88-89°C: too high a water temperature will make it bitter and hard to swallow, while too low a water temperature will make it bland and flat.

How to use a 0.85mm No. 20 sieve?

Regarding grind size, Front Street determines it through sieving, based on the grinding recommendations provided by the Specialty Coffee Association of America SCA for pour-over coffee, and then verified through actual practice. If there is no powder sieve at home, Front Street Coffee (FrontStreet Coffee) recommends judging by observing the water flow speed: if the water flow is too fast, the powder is coarse; if the water flow is too slow, the powder is fine.

First prepare 10g of coffee beans for grinding, initially set a grind size by referring to the size of fine granulated sugar and coarse granulated sugar, then pour it into the sieve, cover it, shake left and right, and let the coffee powder pass through the sieve into the powder receiving tray below until no more coffee powder passes through the sieve, which counts as completing the sieving. Next, prepare an electronic scale and a container and tare it to zero, then pour the sieved coffee powder into the container and weigh it: 8g sieved out is medium-fine grind, 7g sieved out is 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 is Front Street Coffee's (FrontStreet Coffee) sieving data for different extraction methods obtained through many practical brewing trials, for 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 uniform grind size

The ground particles should be uniform. After coffee beans are ground into powder, the distribution of particle coarseness is closely related to the quality of the coffee beverage. The more concentrated the particle coarseness is within the target range, the more uniform the grind, and the better the flavor that can be presented. If there are too many coarse particles, the good flavors hidden inside the coffee cannot be brewed out; if there are too many fine particles, the coffee brewed will taste too muddled and too bitter. If the uneven grinding is relatively serious, Front Street recommends replacing the grinding device.

The above is Front Street Coffee's (FrontStreet Coffee) related explanation on the grinding degree of coffee bean powder, hoping to help coffee enthusiasts who want to understand this knowledge, so that in the future they can correctly adjust the coarseness of coffee powder when extracting coffee.

For more specialty coffee beans, please add the private WeChat Front Street Coffee (FrontStreet Coffee), WeChat ID: kaixinguoguo0925

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