Grind Size Savvy: A Simple Guide to Perfect Coffee Extraction

Question: What’s a simple way to tell if my coffee grinder might be too coarse or too fine for the brewing method I’m using?

Achieving the perfect cup of coffee often hinges on a seemingly small detail: the grind size of your beans. While precise measurements are the domain of professional baristas and advanced home brewers, a simple observation of your coffee grounds and the resulting brew can offer significant clues as to whether your grinder is set too fine or too coarse for your chosen brewing method.

The Visual and Tactile Clues

One of the most straightforward ways to assess your grind is through its physical appearance and feel. For methods like pour-over or drip coffee, a medium grind is generally recommended, resembling coarse sand. If your grinder is producing grounds that look like powder or feel slick and sticky, it’s likely too fine. This fine particulate matter, often referred to as ‘fines,’ can lead to over-extraction and a bitter taste. Conversely, if the grounds resemble pebbles or feel distinctly gritty, your grinder is probably set too coarse. This can result in under-extraction, producing a weak, watery, and sour cup of coffee.

For espresso, the requirements are significantly more nuanced. Espresso extraction is a dynamic process where factors like flow rate, particle size, and temperature play critical roles [6]. A grind that is too fine for espresso can cause the water to struggle to pass through the coffee bed, leading to excessive pressure buildup and channeling, ultimately resulting in a bitter and astringent shot. On the other hand, a grind that is too coarse will allow water to pass through too quickly, leading to an under-extracted shot with little body and a sour taste. The presence of ‘fines’ is particularly critical in espresso extraction dynamics, influencing the overall extraction process [8].

Observing Extraction Behavior

The brewing process itself can offer tell-tale signs of an inappropriate grind size. If you’re using a pour-over device and the water is taking an unusually long time to drip through, or if the brewer appears to be clogging, your grind is likely too fine. This is because the fine particles are too densely packed, restricting water flow. On the other hand, if the water rushes through the coffee bed with little resistance, and the resulting brew is weak, the grind is probably too coarse. The authors of a study on cold brew coffee noted the effect of grinding on extraction time and flavor characteristics, suggesting a direct correlation between grind size and extraction efficiency [7].

For methods like French press, a coarser grind is generally preferred. If you find that your French press is difficult to plunge, or if the resulting coffee is muddy and silty, your grind may be too fine. If the plunge is effortless and the coffee tastes weak and underdeveloped, it’s a strong indicator that the grind is too coarse.

The Taste Test: A Final Arbiter

Ultimately, the taste of your coffee is the most definitive indicator. Over-extraction, often caused by a grind that is too fine, typically results in a bitter, astringent, or even burnt flavor profile. This occurs because the water has had too much contact time with the coffee grounds, extracting undesirable compounds. Under-extraction, usually due to a grind that is too coarse, leads to a sour, weak, and thin-bodied coffee. The aim is to find a grind size that allows for balanced extraction, yielding a cup with a pleasant acidity, sweetness, and body. Research into coffee quality has consistently shown the importance of various factors, including processing and origin, in influencing sensory attributes [3, 4, 5], but proper grind size remains a fundamental variable for optimal extraction regardless of these other factors.

In conclusion, while dedicated tools can offer precise grind measurements, paying close attention to the texture of your grounds and observing how your coffee brews—both in terms of flow rate and final taste—provides a simple yet effective method for determining if your grinder settings are aligned with your brewing method. Adjusting incrementally based on these observations will lead you closer to that perfect cup.

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] — Benedikt K L Schmieder, Verena B Pannusch, Lara Vannieuwenhuyse, Heiko Briesen, Mirjana Minceva — Influence of Flow Rate, Particle Size, and Temperature on Espresso Extraction Kinetics. — 2023-Jul-28 — https://pubmed.ncbi.nlm.nih.gov/37569140/ [7] — Nancy Cordoba, Laura Pataquiva, Coralia Osorio, Fabian Leonardo Moreno Moreno, Ruth Yolanda Ruiz — Effect of grinding, extraction time and type of coffee on the physicochemical and flavour characteristics of cold brew coffee. — 2019-Jun-11 — https://pubmed.ncbi.nlm.nih.gov/31186459/ [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/