Dialing In: Adjusting Your Coffee Brew When Grind Size Changes

Question: What’s an effective way to adjust my coffee brewing method when the beans are ground finer or coarser than usual?

The Foundation of Grind Size

The size of your coffee grounds is a primary determinant of extraction rate. A finer grind offers more surface area for water to interact with, leading to faster extraction. Conversely, a coarser grind presents less surface area, resulting in slower extraction. Understanding this fundamental principle is key to adjusting your brewing method when your grind size is not ideal.

Navigating Finer Grinds

When your coffee beans are ground finer than usual, the increased surface area can lead to over-extraction if other brewing parameters remain unchanged. Over-extraction often manifests as bitterness and astringency. To counteract this, you generally need to shorten your brewing time. This reduces the contact time between the water and the coffee grounds, mitigating the excessive extraction of soluble compounds. Additionally, consider slightly lowering your brew water temperature. Excessively hot water can exacerbate the extraction of bitter compounds, particularly with finer grinds [2, 5]. The goal is to achieve a balanced extraction that highlights the desirable flavor precursors, such as those contributing to nutty or chocolatey notes, rather than overwhelming them with bitterness [4].

Adapting to Coarser Grinds

Conversely, a coarser grind means less surface area, which can result in under-extraction if the brewing parameters are not adjusted. Under-extraction typically leads to a weak, sour, or underdeveloped cup. To achieve a more balanced extraction with coarser grounds, you should extend your brewing time. This allows the water more opportunity to dissolve the desirable flavor compounds. Furthermore, increasing your brew water temperature can be beneficial. Hotter water is more efficient at extracting solubles, helping to draw out the full spectrum of flavors from the less finely ground coffee [5]. This adjustment is important for capturing the aromatic notes and sensory attributes that make coffee appealing [2, 3].

Fine-Tuning the Espresso Exception

Espresso brewing presents a particular case where grind size is exceptionally critical. The presence of very fine particles, often referred to as “fines,” significantly influences espresso extraction dynamics [8]. While generally a finer grind is used for espresso to create the characteristic crema, deviations can be tricky. For instance, if espresso grounds become too fine, it can lead to channeling and over-extraction, impacting the foam quality [1]. If they become too coarse, the espresso may be weak and lack body. Adjustments here often involve a very delicate interplay of grind size, dose, and brew time, with water pressure and temperature also playing crucial roles [6].

In conclusion, effectively adjusting your coffee brewing method when grind size varies is about managing the balance of extraction. For finer grinds, reduce brew time and potentially water temperature. For coarser grinds, increase brew time and potentially water temperature. These adjustments help ensure that you extract the optimal balance of soluble compounds, leading to a more satisfying and flavorful cup of coffee.

References

[1] — Ernesto Illy, Luciano Navarini — Neglected Food Bubbles: The Espresso Coffee Foam. — 2011-Sep — https://pubmed.ncbi.nlm.nih.gov/21892345/ [2] — Gustavo Galarza, Jorge G Figueroa — Volatile Compound Characterization of Coffee ( — 2022-Mar-21 — https://pubmed.ncbi.nlm.nih.gov/35335365/ [3] — Katarína Poláková, Alica Bobková, Alžbeta Demianová, Marek Bobko, Judita Lidiková, Lukáš Jurčaga, Ľubomír Belej, Andrea Mesárošová, Melina Korčok, Tomáš Tóth — Quality Attributes and Sensory Acceptance of Different Botanical Coffee Co-Products. — 2023-Jul-11 — https://pubmed.ncbi.nlm.nih.gov/37509767/ [4] — Rongsuo Hu, Fei Xu, Liyan Zhao, Wenjiang Dong, Xingyuan Xiao, Xiao Chen — Comparative Evaluation of Flavor and Sensory Quality of Coffee Pulp Wines. — 2024-Jun-27 — https://pubmed.ncbi.nlm.nih.gov/38999011/ [5] — Rongsuo Hu, Fei Xu, Xiao Chen, Qinrui Kuang, Xingyuan Xiao, Wenjiang Dong — The Growing Altitude Influences the Flavor Precursors, Sensory Characteristics and Cupping Quality of the Pu’er Coffee Bean. — 2024-Nov-28 — https://pubmed.ncbi.nlm.nih.gov/39682914/ [6] — Erol Uman, Maxwell Colonna-Dashwood, Lesley Colonna-Dashwood, Matthew Perger, Christian Klatt, Stephen Leighton, Brian Miller, Keith T Butler, Brent C Melot, Rory W Speirs, Christopher H Hendon — The effect of bean origin and temperature on grinding roasted coffee. — 2016-Apr-18 — https://pubmed.ncbi.nlm.nih.gov/27086837/ [7] — Jiashun Jiang, Jingan Yang, Tong Zhu, Yongjin Hu, Hong Li, Lijing Liu — Research on the Quality Variation Patterns During the Fermentation Process of Coffee-Grounds Craft Beer. — 2025-Mar-17 — https://pubmed.ncbi.nlm.nih.gov/40232021/ [8] — Samo Smrke, André Eiermann, Chahan Yeretzian — The role of fines in espresso extraction dynamics. — 2024-Mar-07 — https://pubmed.ncbi.nlm.nih.gov/38453983/