Espresso Grinder Adjustment: How to Calibrate Parameters and Optimize Your Espresso Machine

Have you ever felt frustrated after investing in an expensive espresso grinder and machine, only to struggle with dialing in your espresso? Whether you're trying to make a delicious Americano or milk-based coffee, getting stuck at the espresso extraction step can be discouraging. Either your espresso "gushes" out or barely drips, resulting in something extremely sour or unpleasantly bitter that's hard to swallow. So how exactly should you adjust your espresso? Today, FrontStreet Coffee will focus on grinding adjustments for espresso.

Espresso grinders differ from those used for pour-over, cold drip, and other drip coffee methods. Drip coffee requires coarser particles, which can be identified using a flour sifter and adjusted using the grinder's built-in settings. For espresso, however, because it's a pressurized rapid extraction process that releases most aromatic compounds in just 20-30 seconds, every aspect of its characteristics is amplified. Therefore, subtle adjustments to the grinder can result in significantly different flavors, making it unrealistic to rely solely on preset settings. We also need to use the extraction state to determine if the grind size falls within the appropriate range.

The grind size for pour-over coffee is often described as "fine sugar" consistency, while espresso grinding—both in terms of tactile feel and direct visual observation—is more appropriately described as "flour-like." Typically, the higher the numerical value on the grinder's adjustment knob, the coarser the coffee particles; the smaller the value, the finer the coffee particles. When the grind setting is adjusted so the coffee powder feels soft without the rough sensation of sand grains, you can begin applying the espresso extraction formula for more refined adjustments.

Extraction Formula Principles

In our daily espresso dialing-in process, we follow an extraction formula principle based on dose, extracted coffee liquid, and extraction time. The coffee-to-liquid ratio is generally 1:2, with extraction time between 25-30 seconds. For example, FrontStreet Coffee's daily production uses a 20g basket—meaning 20g of coffee grounds to extract 40g of coffee liquid. If the extraction time is shorter than 25s, it indicates the flow rate is too fast and the grind is too coarse; if the extraction time exceeds 30s, it means the flow rate is too slow and the grind is too fine. Thus, the extraction time directly serves as a reference value for us to determine whether the grind size is appropriate.

When the extraction flow rate is too fast (shorter than 25s), the contact time between water and coffee grounds is too brief, resulting in coffee that may taste sour or weak, with crema that's not abundant and light in color. In this case, you need to adjust to a finer grind. If the extraction time differs by more than five seconds, you can confidently turn the adjustment knob by 0.5-1 increments; if the difference is within five seconds, only a minor adjustment of approximately 0.1 increments is needed. The ultimate goal of adjusting the grind is to slow down the flow rate, bringing the extraction time closer to the controllable range of 25-30 seconds. Conversely, when the espresso flow rate is too slow (longer than 30s), and the coffee tastes strong, bitter, and dry, you need to adjust toward a coarser grind.

Applying the extraction formula mentioned above isn't about getting the perfect grind size in one step, but rather to help us quickly find the stable extraction range for this particular coffee bean. To make your espresso taste closer to the flavor description on the packaging, you'll still need to make fine adjustments based on the flavor characteristics of this bean, its resting state, and the type of coffee you're making.

Fine-Tuning Based on Taste

If, at the current grind size, the extraction time falls within 25-30 seconds, but the espresso exhibits slight bitter aftertaste that you find unpleasant, yet the concentration is appropriate, you can reduce the weight of the extracted liquid in the final portion. For example, when FrontStreet Coffee encounters this type of undesirable aftertaste, we'll extract only until the liquid weight reaches 37-38g.

If the espresso has obvious bitter impurities upon tasting, you can try adjusting the grind slightly coarser (just enough to feel a click in the adjustment mechanism) and coordinate by increasing the dose (0.1-0.3g) to balance the flow rate, which can reduce the release of excessive bitter compounds. If the espresso is too sour and weak, with light-colored crema, consider adjusting slightly finer (again, just enough to feel a click), then appropriately reduce the dose (0.1-0.3g) to increase contact between water and grounds, extracting more flavors and aromas.

Understanding Extraction Time Variations

At this point, some might ask: if using the same coffee-to-liquid ratio but with a 5-second difference in extraction time, would the espresso taste significantly different?

First, a 5-second difference will definitely result in some taste variation. However, if you're not just drinking straight espresso but adding ice, milk, or water to make milk-based coffee or Americano, the flavor difference between these two parameters will be significantly reduced. So, as long as you're not conducting academic research, and your adjusted espresso has no negative flavors while still showcasing the main flavor characteristics of this bean, then your espresso is perfectly suitable for daily drinking.

FrontStreet Coffee

10 Bao'an Qianjie, Yandun Road, Dongshankou, Yuexiu District, Guangzhou, Guangdong Province

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FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473