How fine should I grind coffee for French press?

The common misconception regarding French press brewing is that grind size is solely a flavor-tuning knob. In reality, it is a mechanical necessity dictated by the device's filtration system. Because a French press uses a metal mesh rather than paper, it cannot effectively trap 'fines'—the microscopic dust created during the grinding process. If you grind too fine, these particles bypass the filter, creating a gritty, silty mouthfeel that masks the delicate acidity and sweetness the producer worked so hard to cultivate. From a producer's perspective, the goal of the French press is to showcase the coffee's body and texture. By utilizing a coarse grind, you increase the surface area just enough to allow for a four-minute immersion, which extracts the oils and heavier compounds characteristic of the origin. If you find your brew lacks depth, the solution is often to increase the brew ratio or water temperature rather than grinding finer, which risks clogging the mesh and over-extracting the coffee. While some modern brewing theories suggest finer grinds for higher extraction, this often leads to a 'muddy' cup that obscures the terroir. Always prioritize a high-quality burr grinder to ensure particle size uniformity; inconsistent grinds—where boulders and dust coexist—will inevitably lead to a cup that is simultaneously sour and bitter, regardless of your target grind setting.