How do I adjust grind size for a V60?

The Hario V60 is a high-flow dripper, meaning its large bottom aperture offers minimal mechanical resistance to water. Consequently, the 'filter' is not just the paper, but the bed of coffee grounds itself. Adjusting grind size is the most effective lever for managing this flow. A common misconception is that there is a 'universal' setting; in reality, the optimal grind is a moving target dictated by the coffee’s density, roast level, and the specific paper filter used. Light roasts, which are denser and harder to extract, generally require a finer grind to increase surface area and contact time. Conversely, dark roasts are more porous and prone to bitterness, necessitating a coarser grind to prevent over-extraction. From a producer’s perspective, the goal is to highlight the inherent terroir of the bean. If your grind is too fine, you create 'fines' that migrate to the bottom, clogging the paper and causing uneven extraction—a phenomenon that masks the delicate acidity and floral notes that farmers work so hard to preserve. When dialing in, ignore the numbers on your grinder dial, as these are arbitrary. Instead, focus on the relationship between particle size and draw-down time. If the cup lacks sweetness or feels thin, your grind is likely too coarse, allowing water to bypass the coffee. If the finish is astringent or dry, you have likely created too many fines, leading to over-extraction. Treat the grind as a tool to balance the flow rate, ensuring the water spends enough time with the grounds to dissolve the desired sugars without pulling out the harsh, woody compounds.